Module 36: Dermoscopy in General Dermatology -- Inflammatory Dermatoses (Inflammoscopy)
1. Learning Objectives
After completing this module, the learner should be able to:
- Define inflammoscopy and explain its role as an expanding frontier of dermoscopy beyond tumor diagnosis, integrating dermoscopic clues with clinical context and patient history.
- Enumerate the five main dermoscopic parameters evaluated in inflammatory dermatoses (vascular morphology, vascular arrangement, follicular alterations, other structures, and specific clues) according to expert consensus.
- Recognize and differentiate the key vascular patterns seen in inflammatory skin diseases, including dotted, linear, branching, coiled/glomerular, polygonal, tortuous, and spermatozoon-like vessels, and correlate each with specific diagnoses.
- Distinguish psoriasis from dermatitis dermoscopically using vessel distribution (regular vs. patchy), vessel morphology (dotted/glomerular vs. subtle dotted), and scale characteristics (diffuse white vs. yellow sero-crusts).
- Identify Wickham striae and their subtypes (reticular, linear, annular, radial, clustered) as the dermoscopic hallmark of lichen planus, and explain the histopathologic correlate of orthokeratosis overlying wedge-shaped hypergranulosis.
- Recognize the dermoscopic features of granulomatous diseases (sarcoidosis, granuloma annulare, necrobiosis lipoidica, lupus vulgaris), emphasizing orange-yellowish structureless areas corresponding to granulomatous infiltrate.
- Describe the dermoscopic approach to the "red scaly patch" differential, including psoriasis, dermatitis, pityriasis rosea, pityriasis rubra pilaris, mycosis fungoides, and neoplastic mimics (Bowen disease, basal cell carcinoma).
- Apply dermoscopic criteria to monitor treatment response in inflammatory conditions, recognizing hemorrhagic dots as a predictor of favorable psoriasis response and fine linear vessels as an early sign of steroid-induced atrophy.
2. Prerequisites
- Module 01: Introduction and Principles of Dermoscopy (understanding of dermoscopic equipment, polarized vs. nonpolarized dermoscopy, and basic dermoscopic terminology)
- Module 02: Basic dermoscopic structures and colors (understanding of dots, globules, lines, structureless areas, and vascular structures)
3. Key Concepts
3.1 Inflammoscopy -- Definition and Scope
Inflammoscopy is the application of dermoscopy to the diagnosis and monitoring of inflammatory skin diseases. During the last decade, dermoscopy has expanded well beyond its established role in pigmented lesion triage and tumor diagnosis to become a valuable tool for inflammatory dermatoses and parasitoses. The term recognizes that dermoscopy reveals clinically invisible structures -- vascular patterns, follicular alterations, scale morphology, and pigment distribution -- that, when integrated with clinical examination, history, and patient context, facilitate accurate recognition of numerous inflammatory conditions.
3.2 The Five Main Parameters of Inflammoscopy
According to expert consensus, the following five parameters should be systematically evaluated when examining inflammatory dermatoses with dermoscopy:
| # | Parameter | Description |
|---|---|---|
| 1 | Morphology of vascular structures | Shape of individual vessels (dotted, linear, branching, coiled/glomerular, polygonal, tortuous, spermatozoon-like) |
| 2 | Arrangement of vascular structures | Distribution pattern (regular/symmetric vs. patchy/asymmetric, clustered, peripheral, diffuse) |
| 3 | Follicular alterations | Follicular plugs, perifollicular halos, dilated follicles, keratotic plugs |
| 4 | Other structures | Scales (white, yellow, peripheral collarette), crusts, structureless areas (orange, yellow, white, brown), pigmented structures |
| 5 | Specific clues | Pathognomonic or highly specific features (e.g., Wickham striae, polygonal vessels, stellate ulceration, Demodex tails) |
3.3 Specific vs. Nonspecific Criteria
While some dermoscopic criteria are considered highly specific for certain dermatoses (e.g., Wickham striae for lichen planus, polygonal vessels for rosacea), others are "nonspecific" and shared among multiple conditions (e.g., dotted vessels). In the latter scenario, co-evaluation of clinical and dermoscopic clues is necessary to reach a definitive diagnosis.
3.4 Key Terminology Reference
| Term | Definition |
|---|---|
| Inflammoscopy | Application of dermoscopy to inflammatory skin diseases |
| Dotted vessels | Tiny red punctate vessels seen end-on; correspond to vertically oriented capillaries in dermal papillae |
| Glomerular vessels | Coiled/tortuous vessels resembling renal glomeruli; specific to psoriasiform hyperplasia |
| Polygonal vessels | Linear vessels that intersect to form polygons; highly specific for rosacea |
| Spermatozoon-like vessel | Short linear vessel with a red dot on one end; described in mycosis fungoides |
| Wickham striae | Intersecting white lines forming a network; dermoscopic hallmark of lichen planus |
| Sero-crusts | Dried yellow serum on the epidermal surface; dermoscopic hallmark of dermatitis/eczema |
| Apple-jelly nodules | Orange-yellowish structureless areas corresponding to granulomatous infiltrate |
| Stellate ulceration | Star-shaped central erosion; hallmark of Grover disease |
| Trizonal concentric pattern | Three concentric zones (central brown-yellow area, white keratotic collarette, outer erythematous halo); hallmark of perforating dermatoses |
| Cornoid lamella | Histopathologic hallmark of porokeratosis; seen dermoscopically as a double-edged scaly rim ("white track") |
| Demodex tails | White follicular spines protruding from follicles; indicate demodicidosis |
| Auspitz sign (dermoscopic) | Dotted vessels revealed after mechanical removal of psoriatic scale |
4. Core Content
4.1 Dermatitis / Eczema
4.1.1 General Pattern
The typical dermoscopic pattern of all types of dermatitis consists of:
- Dotted vessels in a patchy distribution: Unlike psoriasis, the dotted vessels in dermatitis are subtle and follow a patchy, asymmetric arrangement. Histopathologically, this reflects asymmetric papillomatosis and thinning of the rete ridges.
- Yellow scales/sero-crusts: Considered the dermoscopic hallmark of dermatitis. Histopathologically, these correspond to spongiosis and dried serum on the epidermal surface.
4.1.2 Evolutionary Changes
The dermoscopic appearance of dermatitis varies with disease stage:
| Phase | Scale Characteristics | Vascular Features |
|---|---|---|
| Acute | Yellow scales/sero-crusts almost always present (prominent spongiosis) | Dotted vessels, subtle |
| Subacute | Yellow scales/crusts gradually decrease | Dotted vessels, subtle |
| Chronic (lichenification) | Yellow scales almost absent | Dotted vessels less prominent |
4.1.3 Chronic Hand Eczema
Chronic hand eczema is characterized by:
- Brownish and orange-yellowish dots/globules (resulting from spongiotic vesicles)
- Orange-yellowish crusts
4.1.4 Histopathologic Correlation
The asymmetric papillomatosis and irregular thinning of the rete ridges in dermatitis produce the patchy, asymmetric vessel distribution -- in direct contrast to psoriasis, which has homogeneous and even acanthosis and papillomatosis of the epidermis.
4.2 Seborrheic Dermatitis
Like any other type of dermatitis, seborrheic dermatitis displays:
- Dotted vessels in a patchy distribution
- Fine yellowish scales (occasionally white scales may be present)
- On the scalp: linear vessels (as opposed to scalp psoriasis, which shows coiled or tortuous vascular structures)
Key differential diagnostic role: Dermoscopy is particularly useful for discriminating seborrheic dermatitis from other facial and scalp inflammatory diseases:
| Condition | Distinguishing Dermoscopic Feature |
|---|---|
| Seborrheic dermatitis | Dotted vessels, yellowish scales |
| Rosacea | Polygonal vessels (linear vessels forming polygons) |
| Discoid lupus erythematosus | Follicular criteria (keratin plugs, perifollicular white halos) |
| Sarcoidosis | Orange color and linear vessels |
| Scalp psoriasis | Coiled/tortuous vascular structures |
Check Your Understanding
What does the term 'inflammoscopy' mean, and how does it differ from traditional dermoscopy?
Inflammoscopy is the application of dermoscopy to the examination of inflammatory skin diseases (dermatoses), as opposed to its traditional use for evaluating tumors and neoplastic lesions. It uses the same dermoscopic equipment but evaluates different features: vascular patterns, scale distribution, follicular patterns, and specific morphologic signs associated with inflammatory conditions.
Clinical Scenario
A 40-year-old man presents with an erythematous, scaly patch on the right shin that has been present for 3 months. Clinically, the differential diagnosis includes psoriasis, nummular eczema, and superficial BCC. Dermoscopy reveals regularly distributed dotted vessels arranged in a homogeneous pattern over a light red background, with overlying diffuse white scales. No arborizing vessels, leaf-like structures, or yellow-orange clods are seen.
Which dermoscopic features support psoriasis over the other differential diagnoses?
Psoriasis (plaque type)
The combination of regularly distributed dotted vessels on a light red background with diffuse white scales is the classic dermoscopic pattern of psoriasis. The key discriminating feature is the regular, symmetric distribution of the dotted vessels, which reflects the uniform elongation of dermal papillae and dilated capillary loops characteristic of psoriasiform hyperplasia. Nummular eczema would show patchy dotted vessels with yellow sero-crusts and scales in a less organized distribution. Superficial BCC would show arborizing (tree-like) vessels, leaf-like structures, or spoke-wheel areas -- none of which are present here. The absence of any vessel morphology other than dotted vessels further supports psoriasis, as the presence of non-dotted vessels should challenge the diagnosis.
4.3 Psoriasis
4.3.1 Classic Dermoscopic Pattern
Psoriasis was the first inflammatory skin disease to be explored dermoscopically and remains the paradigmatic condition for inflammoscopy. The typical pattern consists of:
- Regularly distributed dotted, globular, or coiled (glomerular) vessels over a light red background
- White scales (diffuse)
Histopathologic correlation: This characteristic pattern corresponds to epidermal psoriasiform hyperplasia with elongated rete ridges and spiraled capillaries vertically oriented in the dermal papillae.
4.3.2 Dotted Vessels as the Hallmark
The presence of dotted vessels is the hallmark of psoriasis. Key principles:
- In clinically suspect lesions where psoriasis is in the differential, the presence of vessels other than dotted vessels should challenge the diagnosis of psoriasis.
- Dotted vessels are found in numerous inflammatory diseases, but their symmetric and homogeneous distribution is highly indicative of psoriasis or other dermatoses with psoriasiform hyperplasia.
- The regular distribution reflects the symmetric elongation of dermal papillae and uniform thinning of rete ridges.
4.3.3 Dermoscopic Auspitz Sign
Thick superficial scales may impede visualization of vascular structures. Mechanical removal of scales or application of isopropyl alcohol often reveals the dotted vessels -- the dermoscopic Auspitz sign.
4.3.4 Red Globular Rings Pattern
A less frequent vessel distribution is the network-like pattern (syn. plexus-like or "red globular rings" pattern). This closely simulates the vessels of clear cell acanthoma, but in the context of inflammatory diseases, it is considered highly specific for psoriasis.
4.3.5 Site-Specific Variations
The vascular pattern of psoriasis remains unaltered irrespective of body site or clinical subtype. However, scale amount and thickness vary by anatomic location:
| Site/Subtype | Dermoscopic Features |
|---|---|
| Scalp psoriasis | Coiled/tortuous vessels, signet ring vessels, red loops, punctate hemorrhage, pigmentation (perifollicular, honeycomb pattern), white/yellow scales. May need mechanical scale removal to see vessels. |
| Palmoplantar pustular psoriasis | Scales, dotted vessels, underlying pustules may be revealed |
| Inverse psoriasis / psoriatic balanitis | Regularly distributed dotted vessels WITHOUT scales (hyperkeratosis absent) |
| Erythrodermic psoriasis | Diffuse reddish background with dotted/glomerular vessels and white scales |
| Guttate psoriasis | Same vascular pattern as plaque psoriasis |
4.3.6 Psoriasis vs. Neoplastic Mimics
Using dermoscopic criteria, the discrimination of psoriasis from Bowen disease and basal cell carcinoma is strongly enhanced. The regularly distributed dotted vessels of psoriasis are distinct from the glomerular/polymorphous vessels of Bowen disease and the arborizing vessels of BCC.
4.3.7 Treatment Monitoring
Dermoscopy serves as a tool to assess treatment response in psoriasis:
- Hemorrhagic dots: Represent an early predictor of favorable response to systemic agents (multicentric study evidence).
- Fine linear vessels: Represent an initial sign of steroid-induced skin atrophy in patients treated with topical steroids.
Key Takeaways
- Inflammoscopy (dermoscopy of inflammatory skin diseases) evaluates vessel morphology, vessel arrangement, scale color/distribution, and specific patterns to narrow the differential diagnosis.
- Regular dotted vessels in a uniform distribution are the hallmark vascular pattern of psoriasis, corresponding to dilated capillary loops in elongated dermal papillae.
- White diffuse scale is characteristic of psoriasis, while yellow scale suggests seborrheic dermatitis and white-yellow adherent scale suggests eczema.
4.4 Lichen Planus
4.4.1 Wickham Striae -- The Dermoscopic Hallmark
The dermoscopic hallmark of lichen planus (LP) is Wickham striae (WS) -- intersecting white lines forming a network, mainly present in the center of the lesion. The detection of WS is strongly suggestive of LP.
Subtypes of Wickham striae:
| Subtype | Description |
|---|---|
| Reticular | Most common; intersecting white lines forming a net-like pattern |
| Linear | Parallel or single white lines |
| Annular | White lines forming ring-like structures |
| Radial | White lines radiating from center outward |
| Clustered | Groups of white dots/short lines |
Histopathologic correlate: WS correspond to orthokeratosis above zones of wedge-shaped hypergranulosis.
4.4.2 Vascular Structures
Vascular structures are frequent in LP:
- Typically dotted or short linear vessels
- Distributed along the peripheral edge of the Wickham striae
4.4.3 Lichen Planus Pigmentosus (Late LP)
In late LP or LP pigmentosus:
- Multiple blue/gray granules or structureless brown areas represent a frequent finding
- These correspond to melanophages in the upper dermis (pigment incontinence)
4.4.4 Hypertrophic Lichen Planus
Hypertrophic variants may show:
- Comedo-like structures filled with roundish corneal masses
Check Your Understanding
What dermoscopic vascular pattern is characteristic of psoriasis?
Psoriasis characteristically shows regularly distributed dotted vessels (also called bushy capillaries or glomerular vessels) on a red background, arranged in a uniform pattern over the plaque surface. White scale overlies the vascular pattern. This regular dotted vessel pattern reflects the dilated and elongated capillary loops in the dermal papillae that are a histologic hallmark of psoriasis.
Clinical Scenario
A 65-year-old woman presents with violaceous, polygonal, flat-topped papules on her wrists and shins. Dermoscopy reveals Wickham striae -- white crossing lines forming a reticular (network-like) pattern -- overlying a violaceous background. Peripheral dotted and linear vessels are visible at the margins. Yellow-brown globules/dots (corneal layer modifications) are also noted.
What is the diagnosis, and what is the histopathologic correlate of Wickham striae?
Lichen planus
Wickham striae are the pathognomonic dermoscopic feature of lichen planus, appearing as white crossing lines, streaks, or reticular structures. Histopathologically, they correspond to focal areas of hypergranulosis (thickening of the granular layer) overlying a band-like lymphocytic infiltrate at the dermoepidermal junction. The violaceous background reflects the dermal inflammation and pigment incontinence. Several morphologic variants of Wickham striae exist: reticular (most common), linear, annular, round, leaf-venation, and radial streaming patterns. The yellow-brown globules correspond to compact orthokeratosis or corneal layer modifications. Wickham striae distinguish lichen planus from other violaceous dermatoses such as drug eruptions or secondary syphilis, which lack this specific feature.
4.5 Lichen Sclerosus
Lichen sclerosus (LS) has distinct patterns based on location:
| Type | Dermoscopic Pattern |
|---|---|
| Genital LS | White structureless areas combined with dotted and linear vessels |
| Extragenital LS | White structureless areas with keratotic follicular plugs simulating comedo-like openings |
The follicular keratotic plugs of extragenital LS are particularly useful for differentiating it from other hypopigmented dermatoses, including morphea and vitiligo.
4.6 Rosacea
4.6.1 The Polygonal Vessel Pattern
Rosacea is dermoscopically typified by a highly characteristic vascular pattern: intersecting linear vessels that form polygons (polygonal vessels). This pattern is highly specific for rosacea compared with other dermatoses in its differential diagnosis.
4.6.2 Subtypes
| Rosacea Subtype | Dermoscopic Features |
|---|---|
| Erythemato-telangiectatic | Polygonal vessels predominant and most clearly seen |
| Papulopustular | Polygonal vessels (less prevalent), combined with visible pustules |
| Glandular (phymatous) | Polygonal vessels less evident; follicular criteria may predominate (dilated follicles with keratin plugs) |
4.6.3 Demodicidosis
A rosacea-like eruption associated with Demodex folliculorum (demodicidosis) shows:
- White follicular "spines" protruding out of the follicle -- termed Demodex "tails"
- Often associated with polygonal vessels
Check Your Understanding
How can dermoscopy differentiate between psoriasis and eczema/dermatitis?
Psoriasis shows regularly distributed dotted vessels in a uniform pattern with white scale. Eczema/dermatitis shows patchy distributed dotted vessels (less regular), yellow scale or serous crusts, and may show brown-orange dots (spongiotic vesicles). The regularity of vessel distribution is the key differentiating feature: regular in psoriasis, irregular/patchy in eczema.
4.7 Granulomatous Diseases
Granulomatous diseases share the key dermoscopic feature of orange-yellowish structureless areas (the dermoscopic equivalent of "apple-jelly nodules" on diascopy), corresponding to the dense, compact granulomatous infiltrate. However, additional features and vessel patterns allow some differentiation.
4.7.1 Granuloma Annulare
The dermoscopic pattern of granuloma annulare (GA) depends on the histologic subtype:
| GA Subtype | Dermoscopic Pattern | Histopathologic Correlation |
|---|---|---|
| Palisading | Yellowish-to-orange structureless areas | Well-formed palisading granulomas |
| Interstitial | Pink-reddish background with subtle, unfocused vessels (dotted, short linear, and linear branching); absence of orange-yellowish areas | Absence of well-formed granulomas |
4.7.2 Sarcoidosis
Cutaneous sarcoidosis is characterized by:
- Orange areas (diffuse or focal) corresponding to granulomatous infiltrate
- Linear branching vessels
- Additional features: dotted and glomerular vessels (lesser degree), pigmented structures, follicular plugs, scales, dilated follicles, milia-like cysts, and crystalline structures
Important limitation: A very similar dermoscopic pattern typifies other granulomatous disorders such as lupus vulgaris and cutaneous leishmaniasis. Dermoscopy currently cannot reliably differentiate among these granulomatous disorders.
4.7.3 Necrobiosis Lipoidica
The most frequent dermoscopic pattern consists of:
- Diffuse structureless orange-yellowish color or focal orange-yellowish structures
- Vascular structures whose morphology varies with disease evolution:
| Disease Stage | Vessel Morphology |
|---|---|
| Early | Dotted, globular, and glomerular vessels |
| Late | Fine, linear, and branching vessels forming a dense vascular plexus (may be visible macroscopically) |
4.8 Discoid Lupus Erythematosus
The dermoscopic pattern of discoid lupus erythematosus (DLE) depends on disease stage, with follicular criteria predominating in earlier stages and atrophy-related structures in later stages:
| Disease Stage | Dermoscopic Features | Histopathologic Correlation |
|---|---|---|
| Early | Follicular plugs + perifollicular whitish halos; diffuse hyperkeratosis may be present | Early perifollicular fibrosis |
| Intermediate | Follicular criteria fade; erythema and hyperkeratosis more evident; telangiectatic vessels appear | Atrophic epidermis allows vessel visualization |
| Advanced | Telangiectasia more prominent; gray-brown pigmented granules, dots, globules, or network-like structures | Melanophages in dermis |
| Final | White structureless areas only | Extensive fibrosis |
Key differentials:
- Lupus pernio and lupus vulgaris: Different dermoscopic pattern with absence of follicular alterations
- Actinic keratosis: Erythema interrupted by white follicular openings ("strawberry pattern")
Check Your Understanding
What dermoscopic features help identify lichen planus?
Lichen planus shows characteristic Wickham striae, which appear as white crossing lines (reticular pattern) overlying a pinkish-red or violaceous background. Dotted or linear vessels may be visible at the periphery. The Wickham striae pattern on dermoscopy correlates with the hypergranulosis seen histologically and is the most specific dermoscopic feature of lichen planus.
Key Takeaways
- Wickham striae (white crossing lines) visible under dermoscopy are pathognomonic for lichen planus and correspond to wedge-shaped hypergranulosis in the epidermis.
- Dermoscopic vessel morphology is one of the most diagnostically useful inflammoscopy features: dotted (psoriasis), glomerular (Bowen disease), arborizing (BCC), linear (scleroderma).
- Seborrheic dermatitis shows arborizing vessels with yellow scales, distinguishing it from psoriasis (dotted vessels with white scale) and eczema (patchy dotted vessels with yellow-white crust).
4.9 Grover Disease (Transient Acantholytic Dermatosis)
The dermoscopic hallmark of Grover disease is the "stellate ulceration":
- A central stellate-shaped (star-shaped) yellow or brownish area surrounded by a whitish halo
- Background erythema may also be present
4.10 Lymphomatoid Papulosis
Lymphomatoid papulosis (LyP) belongs to the spectrum of cutaneous T-cell lymphomas. Its dermoscopic pattern depends on lesion age:
| Lesion Stage | Dermoscopic Features |
|---|---|
| Recent papules/nodules | Dotted or tortuous/irregular vessels over an erythematous background; purpuric spots |
| Later stage | Vessels become less evident, aggregate at periphery of papules |
| Hyperkeratotic lesions | White-yellowish structureless area covering central part |
| Necrotic lesions | Dark brown central eschar |
| Healing/resolved | Brown-gray structureless areas (post-inflammatory pigmentation) |
4.11 Mastocytosis
Different clinical variants display different dermoscopic patterns:
| Variant | Dermoscopic Pattern |
|---|---|
| Maculopapular mastocytosis (urticaria pigmentosa) | Uniform light-brown pigment network |
| Telangiectasia macularis eruptiva perstans | Reticular vessels on erythematous/brownish background; sometimes with brownish network |
| Solitary mastocytoma | Diffuse orange-to-yellowish color or multifocal yellow-to-orange areas |
Both maculopapular and telangiectasia macularis types may also show dotted vessels and thin, tortuous linear vessels. Overlap of dermoscopic criteria exists among different types.
4.12 Mycosis Fungoides
4.12.1 Patch-Stage MF
The most frequent dermoscopic structures are:
- Short-fine, linear, curved vessels (corresponding to dilated dermal vessels)
- Orange-yellowish patchy areas (corresponding to hemosiderin deposits in the dermis)
- Spermatozoon-like structure: A peculiar vessel consisting of a short linear vessel with a red dot on one end
4.12.2 Poikilodermatous MF
Vascular structures are much more prominent.
4.12.3 Erythrodermic MF
- Sparse whitish scales
- Widespread dotted vessels
- A few spermatozoon-shaped vessels
- White-pinkish background
4.12.4 Key Differential: MF vs. Chronic Dermatitis
| Feature | Mycosis Fungoides | Chronic Dermatitis |
|---|---|---|
| Vessel type | Short-fine linear vessels +/- spermatozoa-like vessels | Scattered dotted vessels |
| Patchy areas | Orange-brown patchy areas | Yellow scales |
| Linear vessels | Present | Typically absent |
4.13 Pigmented Purpuric Dermatoses
The group of pigmented purpuric dermatoses (PPDs) includes:
- Schamberg disease
- Majocchi purpura
- Eczematoid purpura of Doukas and Kapetanakis
- Lichen aureus
- Pigmented purpuric lichenoid dermatitis of Gougerot-Blum
Common dermoscopic features (all forms):
- Round to oval, red, purpuric dots and/or globules (extravasated erythrocytes in the dermis) over a brownish to coppery-colored background (dermal hemosiderin deposits)
- Additional features: linear or dotted vessels, white scales, pigmented structures (dots/globules and network)
4.14 Perforating Dermatoses
The group includes elastosis perforans serpiginosa, perforating collagenosis, reactive perforating folliculitis, and acquired perforating dermatosis (Kyrle disease).
Characteristic dermoscopic pattern -- "Trizonal Concentric" Pattern:
Three concentric zones:
- Central zone: Roundish, brown-yellow structureless area
- Middle zone: White keratotic collarette
- Outer zone: Erythematous halo, with or without dotted vessels
Kyrle disease may additionally show peripheral brown pigmentation.
4.15 Pityriasis Lichenoides
4.15.1 Acute Pityriasis Lichenoides (PLEVA)
Dermoscopic findings depend on lesion evolution:
| Phase | Dermoscopic Features |
|---|---|
| Early | Purpuric dots or diffuse hemorrhagic areas, usually toward center of lesion |
| Later | Central amorphous brownish crust |
| Healing | Central white area (fibrosis) |
| All stages | Peripheral rim of pinpoint and/or linear vessels; peripheral collarette of scales with inner free edge |
4.15.2 Chronic Pityriasis Lichenoides
- Central orange-yellowish structureless areas
- Globular or linear vessels
- Diffuse and/or peripheral whitish scaling
Key Takeaways
- Granulomatous diseases (sarcoidosis, granuloma annulare) show orange-yellowish structureless areas (apple-jelly nodules) under dermoscopy corresponding to dermal granulomas.
- Linear vessels (non-arborizing) with a background orange hue are characteristic of sarcoidosis and help differentiate it from BCC (arborizing vessels with blue-gray structures).
- Dermoscopic evaluation of inflammatory conditions can reduce unnecessary biopsies by providing pattern-based diagnosis that correlates well with histopathology.
4.16 Pityriasis Rosea
The herald and secondary patches of pityriasis rosea are dermoscopically identical:
- Fine scales mainly located at the periphery (peripheral collarette)
- Dotted vessels in an asymmetric distribution (a few)
- An orange-yellowish hue may be present
- If eczematous reaction occurs in the background, dermoscopy reveals yellow sero-crusts (eczema features)
4.17 Pityriasis Rubra Pilaris
The most frequent dermoscopic pattern:
- Round to oval yellowish areas surrounded by linear or dotted vessels, often combined with central keratin
- Keratoderma: Variably sized orange area with whitish scale
- Erythrodermic stage: Orange blotches and islands of nonerythematous (spared) skin displaying reticular vessels (as opposed to the dotted vessels of psoriasis)
Key differential: PRP vs. Psoriasis -- In erythrodermic presentations, reticular vessels favor PRP while dotted vessels favor psoriasis.
4.18 Porokeratosis
4.18.1 Main Finding: The "White Track"
- A well-defined, roundish, peripherally white-colored double-edged scaly rim forming a groove, which may be continuous or discontinuous ("white track")
- Corresponds to the cornoid lamella on histopathology
4.18.2 Central Features by Lesion Age
| Lesion Stage | Central Features |
|---|---|
| Active | Dotted or globular vessels |
| Resolving | Blue/gray dots/granules |
| Late | Diffuse white color with or without shiny white lines (epidermal atrophy and dermal fibrosis) |
4.18.3 Ink Test
For difficult-to-visualize lesions, the ink test can accentuate the cornoid lamella:
- Stain the lesion with a surgical marking pen (gentian violet)
- Wipe off with 70% isopropyl alcohol
- Ink remains in the groove, creating a visible ring that confirms the diagnosis
4.19 Prurigo Nodularis
Dermoscopic pattern:
- "White starburst pattern": Radially arranged whitish lines
- Alternative pattern: Peripheral white halo surrounding red-brown crusts with hyperkeratosis, scales, or central erosion
4.20 Urticaria and Urticarial Vasculitis
Both conditions show a network of fine linear vessels over an erythematous background, but can be distinguished:
| Feature | Urticaria | Urticarial Vasculitis |
|---|---|---|
| Vessel pattern | Network of linear vessels alternating with avascular areas | Network of linear vessels |
| Purpuric features | Absent | Purpuric dots/globules (extravasated erythrocytes from vasculitis) |
4.21 Vessel Morphology in Inflammatory Conditions -- Summary
Understanding the morphology and arrangement of vessels is fundamental to inflammoscopy. The following table summarizes the key vascular patterns and their diagnostic associations:
| Vessel Morphology | Description | Associated Conditions |
|---|---|---|
| Dotted (regular) | Tiny punctate vessels in regular, symmetric distribution | Psoriasis (hallmark), psoriasiform hyperplasia |
| Dotted (patchy) | Tiny punctate vessels in patchy, asymmetric distribution | Dermatitis/eczema, seborrheic dermatitis, pityriasis rosea |
| Glomerular/coiled | Tortuous vessels resembling renal glomeruli | Psoriasis, scalp psoriasis |
| Polygonal | Linear vessels intersecting to form polygons | Rosacea (highly specific) |
| Linear branching | Fine branching linear vessels | Sarcoidosis, necrobiosis lipoidica (late), cutaneous sarcoidosis |
| Short-fine linear curved | Short curved linear vessels | Mycosis fungoides (patch stage) |
| Spermatozoon-like | Short linear vessel with red dot on one end | Mycosis fungoides |
| Tortuous/irregular | Irregularly coiled vessels | Lymphomatoid papulosis, scalp seborrheic dermatitis |
| Reticular | Vessels forming a reticular/network pattern | Telangiectasia macularis eruptiva perstans, PRP erythroderma |
| Linear (network) | Fine linear vessels forming a network | Urticaria, urticarial vasculitis |
| Signet ring | Ring-shaped vessels | Scalp psoriasis |
4.22 Scale Characteristics Across Conditions
Scale morphology and distribution provide critical diagnostic clues:
| Scale Type | Characteristics | Associated Conditions |
|---|---|---|
| Diffuse white scales | Thick, diffuse, overlying the entire lesion | Psoriasis |
| Yellow scales/sero-crusts | Dried serum, corresponding to spongiosis | Dermatitis/eczema (hallmark), acute phases |
| Fine yellowish scales | Thin, patchy | Seborrheic dermatitis |
| Peripheral collarette scales | Fine scales at the periphery with inner free edge | Pityriasis rosea, pityriasis lichenoides |
| White keratotic collarette | Annular white rim of scale | Perforating dermatoses (middle zone of trizonal pattern) |
| Sparse whitish scales | Thin, widespread | Erythrodermic mycosis fungoides |
| Peripheral whitish scaling | Diffuse or peripheral | Chronic pityriasis lichenoides |
4.23 Dermoscopic Approach to the "Red Patch" or "Scaly Lesion"
When confronted with an erythematous, scaly patch or plaque, the dermoscopic approach should follow this systematic evaluation:
Step 1 -- Assess vessel morphology and arrangement:
- Regular dotted/glomerular vessels --> Think psoriasis
- Patchy dotted vessels --> Think dermatitis
- Short-fine linear curved vessels --> Think mycosis fungoides
- Polygonal vessels --> Think rosacea
- Linear branching vessels --> Think granulomatous disease
Step 2 -- Evaluate scales and crusts:
- Diffuse white scales --> Psoriasis
- Yellow sero-crusts --> Dermatitis
- Peripheral collarette --> Pityriasis rosea
- Absent scales (mucosal/intertriginous) --> Inverse psoriasis
Step 3 -- Look for specific clues:
- Wickham striae --> Lichen planus
- Orange-yellowish structureless areas --> Granulomatous disease
- Purpuric dots/globules --> PPD or urticarial vasculitis
- Stellate ulceration --> Grover disease
- White starburst --> Prurigo nodularis
- Follicular plugs + white halos --> DLE
- White track (cornoid lamella) --> Porokeratosis
Step 4 -- Integrate with clinical context:
- Distribution pattern, patient age, history, associated symptoms
- Exclude neoplastic mimics (Bowen disease, BCC, clear cell acanthoma)
Key Takeaways
- The inflammoscopy algorithm begins with vessel morphology assessment, then evaluates scale characteristics, background color, and specific patterns to reach a differential diagnosis.
- Combining vessel pattern with scale type achieves moderate-to-high diagnostic accuracy for common inflammatory dermatoses (psoriasis, eczema, lichen planus, seborrheic dermatitis).
- Inflammoscopy is most useful as a triage tool to narrow the differential; histopathologic confirmation remains necessary for atypical presentations and rare conditions.
5. Inflammoscopy Reference Table
| Condition | Key Dermoscopic Features | Main Differential(s) |
|---|---|---|
| Dermatitis (all types) | Dotted vessels (patchy, asymmetric); yellow scales/sero-crusts | Psoriasis, mycosis fungoides |
| Seborrheic dermatitis | Dotted vessels (patchy); fine yellowish scales; linear vessels on scalp | Rosacea, DLE, sarcoidosis, scalp psoriasis |
| Psoriasis | Dotted/globular/glomerular vessels (regular, symmetric); light red background; diffuse white scales | Dermatitis, Bowen disease, BCC, clear cell acanthoma |
| Lichen planus | Wickham striae (reticular white lines); dotted/short linear vessels at periphery of WS | Lichen sclerosus, lichenoid keratosis |
| Lichen planus pigmentosus | Blue-gray granules; structureless brown areas (melanophages) | Post-inflammatory hyperpigmentation |
| Lichen sclerosus (genital) | White structureless areas; dotted and linear vessels | Vitiligo, morphea |
| Lichen sclerosus (extragenital) | White structureless areas; keratotic follicular plugs (comedo-like) | Morphea, vitiligo |
| Rosacea | Polygonal vessels (highly specific); pustules in papulopustular type | Seborrheic dermatitis, DLE, sarcoidosis |
| Demodicidosis | Demodex tails (white follicular spines); polygonal vessels | Rosacea, seborrheic dermatitis |
| Granuloma annulare (palisading) | Yellowish-to-orange structureless areas | Sarcoidosis, necrobiosis lipoidica |
| Granuloma annulare (interstitial) | Pink-reddish background; subtle unfocused vessels (dotted, short linear, branching); NO orange areas | Dermatitis, other inflammatory |
| Sarcoidosis | Orange areas (diffuse/focal); linear branching vessels; crystalline structures | Lupus vulgaris, cutaneous leishmaniasis, GA |
| Necrobiosis lipoidica | Diffuse orange-yellowish color; vessels vary by stage (dotted/globular early; linear branching late) | Sarcoidosis, GA |
| DLE (early) | Follicular plugs; perifollicular whitish halos | Actinic keratosis, sarcoidosis |
| DLE (late) | White structureless areas; telangiectasia; pigmented granules | Morphea, lichen sclerosus |
| Grover disease | Stellate ulceration (star-shaped yellow/brown center + whitish halo) | Darier disease, other acantholytic disorders |
| Lymphomatoid papulosis | Dotted/tortuous vessels; purpuric spots; white-yellow center (later) | Pityriasis lichenoides, insect bites |
| Mastocytosis (UP) | Uniform light-brown pigment network | Melanocytic nevi |
| Mastocytosis (TMEP) | Reticular vessels; erythematous/brownish background | Telangiectatic conditions |
| Mastocytosis (solitary) | Diffuse orange-to-yellowish color | Xanthoma, juvenile xanthogranuloma |
| Mycosis fungoides | Short-fine linear curved vessels; orange-yellowish patchy areas; spermatozoon-like vessels | Chronic dermatitis, parapsoriasis |
| PPDs | Red purpuric dots/globules; brownish-coppery background (hemosiderin) | Stasis dermatitis, vasculitis |
| Perforating dermatoses | Trizonal concentric pattern (central brown-yellow, white collarette, erythematous halo) | Prurigo nodularis, keratoacanthoma |
| PLEVA | Purpuric dots/hemorrhagic areas (center); peripheral collarette scales | Pityriasis rosea, LyP, vasculitis |
| Pityriasis rosea | Peripheral collarette scales; dotted vessels (asymmetric); orange-yellowish hue | Dermatitis, guttate psoriasis, secondary syphilis |
| PRP | Round-oval yellowish areas; linear/dotted vessels; central keratin | Psoriasis (erythrodermic), dermatitis |
| Porokeratosis | White double-edged scaly rim ("white track"); ink test positive | Actinic keratosis, tinea corporis |
| Prurigo nodularis | White starburst pattern (radial white lines); central erosion/crust | Hypertrophic LP, nodular BCC |
| Urticaria | Linear vessel network alternating with avascular areas | Urticarial vasculitis |
| Urticarial vasculitis | Linear vessel network + purpuric dots/globules | Urticaria, leukocytoclastic vasculitis |
6. Inflammatory vs. Neoplastic Lesion Differentiation Table
One of the most important applications of inflammoscopy is distinguishing inflammatory dermatoses from neoplastic mimics. The following table summarizes key differentiating features:
| Feature | Inflammatory Lesions | Neoplastic Lesions |
|---|---|---|
| Vessel morphology | Dotted, glomerular, polygonal, short linear (pattern-specific per condition) | Arborizing (BCC), glomerular/coiled in clusters (Bowen), polymorphous (melanoma), hairpin (keratinizing tumors) |
| Vessel arrangement | Often symmetric, regular (psoriasis) or patchy (dermatitis); distributed across lesion | Often asymmetric, irregular; focal clustering |
| Scale type | White diffuse (psoriasis), yellow sero-crusts (dermatitis), peripheral collarette (PR) | Surface keratin, milia-like cysts, comedo-like openings (SK); ulceration (BCC) |
| Background color | Light red/pink (psoriasis), erythematous | Blue-white veil (melanoma), maple-leaf (BCC), brownish (pigmented tumors) |
| Specific structures | Wickham striae, stellate ulceration, Demodex tails, trizonal pattern | Blue-white structures, pigment network, streaks/pseudopods, leaf-like areas |
| Symmetry | Many conditions show overall symmetric distribution of features | Melanocytic malignancy typically asymmetric |
| Response to treatment | Features improve or resolve with therapy | Persist or progress despite anti-inflammatory treatment |
Key Differential Pairs
| Inflammatory Condition | Neoplastic Mimic | Distinguishing Dermoscopic Clue |
|---|---|---|
| Psoriasis | Bowen disease (SCC in situ) | Psoriasis: regular dotted vessels, white scales. Bowen: glomerular vessels in clusters, scaly surface with scale-free areas |
| Psoriasis | Superficial BCC | Psoriasis: dotted vessels only. BCC: arborizing vessels, shiny white structures, blue-gray ovoid nests |
| Psoriasis | Clear cell acanthoma | Both show "red globular rings" pattern; clinical context and response to treatment distinguish |
| Dermatitis | Patch-stage mycosis fungoides | Dermatitis: dotted vessels + yellow scales. MF: short-fine linear vessels + orange-brown areas + spermatozoon-like vessels |
| DLE | Actinic keratosis | DLE: follicular plugs + perifollicular white halos. AK: "strawberry pattern" (erythema with white follicular openings) |
| DLE | SCC | DLE: follicular criteria evolving to atrophy. SCC: polymorphous vessels, keratin, white structureless areas without follicular pattern |
7. Clinical Pearls
Yellow = spongiosis: Yellow scales and sero-crusts are the dermoscopic hallmark of dermatitis. Their presence should strongly suggest eczematous pathology and their absence in a "dermatitis-like" lesion should prompt reconsideration of the diagnosis.
Regular vessels = psoriasis: Dotted vessels in a regular, symmetric distribution are nearly pathognomonic for psoriasis among inflammatory diseases. Irregular or patchy dotted vessels suggest dermatitis or other conditions.
Remove the scale: Thick psoriatic scale may hide the diagnostic vascular pattern. Mechanical removal or application of isopropyl alcohol reveals the "dermoscopic Auspitz sign" -- the key dotted vessels needed for diagnosis.
Polygonal vessels = rosacea: Among facial inflammatory diseases, the finding of polygonal vessels (linear vessels forming polygons) is highly specific for rosacea and should reliably distinguish it from seborrheic dermatitis, DLE, and facial sarcoidosis.
Orange = granuloma: Orange-yellowish structureless areas indicate granulomatous infiltrate and point toward sarcoidosis, granuloma annulare (palisading), necrobiosis lipoidica, or lupus vulgaris. However, dermoscopy alone cannot differentiate among these granulomatous disorders.
Follicular criteria tell the DLE story: In early DLE, follicular plugs and perifollicular whitish halos are the key findings; in late DLE, white structureless areas from fibrosis predominate. Tracking this progression is diagnostically useful.
Wickham striae confirm LP: The finding of intersecting white lines (Wickham striae) in any of their subtypes (reticular, linear, annular, radial, clustered) is strongly suggestive of lichen planus. Look for peripheral dotted or short linear vessels as a supporting feature.
MF mimics dermatitis -- but the vessels differ: In the crucial differential between early mycosis fungoides and chronic dermatitis, look for short-fine linear curved vessels and spermatozoon-like vessels (MF) vs. scattered dotted vessels with yellow scales (dermatitis).
PRP vs. psoriasis in erythroderma: In erythrodermic patients, reticular vessels with orange blotches and islands of spared skin favor PRP, while dotted vessels with white scales favor psoriasis.
Purpuric dots distinguish vasculitis from urticaria: In urticarial-appearing lesions, the presence of purpuric dots/globules indicates vascular damage (urticarial vasculitis) and excludes simple urticaria, where only a network of linear vessels alternating with avascular areas is seen.
The ink test for porokeratosis: When the characteristic double-edged scaly rim is difficult to visualize, the ink test (gentian violet staining + alcohol wipe) can confirm the diagnosis by trapping ink in the cornoid lamella groove.
Treatment monitoring: Dermoscopy provides objective early indicators of treatment response -- hemorrhagic dots predict favorable psoriasis response to biologics, while fine linear vessels warn of steroid-induced atrophy before it is clinically evident.
Clinical Vignettes
Clinical Scenario A 35-year-old man presents with well-defined erythematous plaques on both elbows covered by thick white scales. Dermoscopy initially shows only thick white scale with no visible vascular pattern. After gentle removal of the scale, dermoscopy reveals uniformly distributed dotted vessels over a light red background. The vessel distribution is regular and symmetric throughout the plaque.
What is the most likely diagnosis?
Diagnosis: Plaque psoriasis.
Clinical Pearl 2: dotted vessels in a regular, symmetric distribution are nearly pathognomonic for psoriasis. Clinical Pearl 3: thick psoriatic scale may hide the diagnostic vascular pattern -- removal reveals the "dermoscopic Auspitz sign" (dotted vessels on erythematous background). The regular distribution distinguishes psoriasis from dermatitis (which shows irregular or patchy dotted vessels). Clinical Pearl 1: the white (not yellow) scales further support psoriasis -- yellow scales would suggest dermatitis. The bilateral elbow distribution is clinically classic.
Clinical Scenario A 52-year-old woman presents with erythematous patches on the forearms that have persisted for over a year, initially diagnosed as chronic eczema. Topical corticosteroids have been ineffective. Dermoscopy reveals short, fine, linear curved vessels and scattered orange-brown areas. Spermatozoon-like vessels are visible in some areas. No yellow scales, regular dotted vessels, or white scales are present.
What is the most likely diagnosis?
Diagnosis: Early mycosis fungoides (MF) -- not chronic dermatitis.
Clinical Pearl 8: in the crucial differential between early MF and chronic dermatitis, look for short-fine linear curved vessels and spermatozoon-like vessels (MF) versus scattered dotted vessels with yellow scales (dermatitis). The absence of yellow scales (Clinical Pearl 1: yellow = spongiosis, the hallmark of dermatitis) and the presence of MF-specific vessel types shifts the diagnosis away from eczema. The orange-brown areas correspond to hemosiderin deposits. Treatment-resistant "dermatitis" should always prompt reconsideration of the diagnosis and dermoscopic re-evaluation. Skin biopsy is warranted for histopathologic confirmation.
Clinical Scenario A 45-year-old woman presents with violaceous, polygonal, pruritic papules on her wrists bilaterally. Dermoscopy reveals intersecting white lines forming a reticular (lace-like) pattern over the surface of the papules. Peripheral dotted and short linear vessels are visible. The background has a violaceous hue.
What is the most likely diagnosis?
Diagnosis: Lichen planus.
Clinical Pearl 7: Wickham striae confirm LP. The intersecting white lines forming a reticular pattern are Wickham striae -- present in several subtypes (reticular, linear, annular, radial, clustered). Peripheral dotted and short linear vessels are a supporting feature. The clinical context of violaceous, polygonal, pruritic papules on the wrists (the classic "5 Ps") combined with dermoscopic Wickham striae is virtually diagnostic. This case demonstrates how dermoscopy can provide rapid, confident diagnosis of inflammatory diseases, potentially avoiding the need for biopsy in classic presentations.
9. Cross-References
| Topic | Chapter/Section | Page(s) |
|---|---|---|
| Infectious diseases (entomodermoscopy) | Chapter 12A | 294--298 |
| Dermoscopic patterns of skin infections | Chapter 12A | 295 |
| Psoriasis (first inflammoscopy target) | Chapter 12B | 304--305 |
| Rosacea and polygonal vessels | Chapter 12B | 306 |
| Granulomatous disorders (sarcoidosis, GA, NL) | Chapter 12B | 300, 302, 306 |
| Lichen planus and Wickham striae | Chapter 12B | 301 |
| Discoid lupus erythematosus | Chapter 12B | 300 |
| Mycosis fungoides | Chapter 12B | 302 |
| Bowen disease and BCC (neoplastic differentials) | Chapter 12B | 305 |
| Treatment monitoring with dermoscopy | Chapter 12B | 305 |
| Dermoscopic patterns of common facial inflammatory diseases | Lallas et al. 2014, Ref. 2 | -- |
| Accuracy of dermoscopic criteria (psoriasis, dermatitis, LP, PR) | Lallas et al. 2012, Ref. 1 | -- |
10. Related Modules
- Module 01: Introduction and Principles of Dermoscopy -- foundational understanding of dermoscopic equipment, optical principles, and terminology required for inflammoscopy evaluation.
- Module 02: Basic Dermoscopic Structures and Colors -- prerequisite knowledge of dots, globules, lines, structureless areas, and vascular structures that form the building blocks of inflammoscopy criteria.
- Module 09: Basal Cell Carcinoma -- understanding of arborizing vessels and other BCC-specific features needed for the inflammatory vs. neoplastic differential.
- Module 11: SCC Spectrum -- includes Bowen disease, a key neoplastic mimic of psoriasis, with its characteristic glomerular vessel pattern.
- Module 13: Vascular Lesions -- deeper understanding of vessel morphology classification and vascular patterns that overlaps with inflammoscopy vessel assessment.
Part of the Dermoscopy Educational Course.