Module 09: Basal Cell Carcinoma

• Most common cutaneous malignancy worldwide; incidence is rising.
• Over 2 million cases diagnosed annually in the United States alone.
• Mortality is negligible, but morbidity can be significant, particularly when tumors are located in cosmetically or functionally sensitive areas (e.g., eyelids) or allowed to grow large.
• The goal of screening is to detect BCCs while their diameter is as small as possible; dermoscopic criteria are the same in large and tiny tumors.

• BCCs present with a wide variety of morphologies ranging from erythematous macules to ulcerated nodules.
• Most BCCs are pink/nonpigmented lesions, but some display pigment and can mimic melanoma or other pigmented lesions clinically.

Parameter	Dermoscopy	Naked Eye
Sensitivity (overall)	85.0%	66.9%
Specificity (overall)	97.2%	98.2%
Sensitivity (pigmented BCC)	91.3%	--
Sensitivity (nonpigmented BCC)	84.3%	--
Specificity (pigmented BCC)	99%	--
Specificity (nonpigmented BCC)	73.2%	--

• The higher specificity for pigmented BCC is attributable to the highly specific pigmented structures visible under dermoscopy.
• The diagnostic method for pigmented BCC: a lesion lacks a pigment network AND displays one or more BCC-specific features. This yields a sensitivity of 93% and specificity of 89-92% for pigmented BCC.

Subtype	Key Clinical Features	Dermoscopic Signature
Nodular BCC	Flesh-colored or translucent papule/nodule, may ulcerate	Arborizing vessels, blue-gray ovoid nests, ulceration, MAY globules (20%)
Superficial BCC	Erythematous macule/thin plaque, often on trunk	Short-fine telangiectasia, leaf-like structures, spoke-wheel/concentric structures, multiple small erosions, in-focus blue-gray dots
Infiltrative/Morpheaform BCC	Scar-like, ill-defined plaque	MAY globules (>50%), shiny white blotches and strands
Pigmented BCC	Any subtype with melanin pigment	Classic pigmented criteria (ovoid nests, globules, leaf-like, spoke-wheel) plus subtype-associated features

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The first systematic dermoscopic study of pigmented BCC by Menzies et al. (2000) established the foundational diagnostic approach: pigmented BCCs lack features of melanocytic tumors (such as a pigment network) and instead display at least one of six specific structures. Subsequent studies expanded the list with variant and supplementary criteria.

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The pigmented structures in BCC arise from BCC tumor islands containing melanin pigment. The first group -- dots, globules, and ovoid nests -- form a size continuum, all corresponding histopathologically to pigmented BCC tumor islands.

4.2.1 Multiple Blue-Gray Dots (In-Focus Dots)

• Morphology: Well-defined, in-focus, pinpoint-sized structures smaller than globules.
• Distribution: Random "bird-shot" scatter pattern.
• Histopathologic correlation: Tiny superficial pigmented BCC tumor islands.
• Subtype association: In the absence of blue-gray globules, ovoid nests, arborizing vessels, and ulceration, their presence is highly suggestive of superficial BCC.
• Key distinction: These are a variant of blue-gray globules (described by Altamura et al., 2010), termed "in-focus dots."

4.2.2 Multiple Blue-Gray Nonaggregated Globules

• Morphology: Well-defined, round to oval structures, blue-gray in color. Larger than dots but smaller than large ovoid nests.
• Key distinction from melanocytic globules:
• In melanocytic lesions: globules are usually found in aggregates of three or more and are brown to black in color.
• In BCC: globules tend not to aggregate and have a blue-gray color.
• Histopathologic correlation: Pigmented tumor islands (nodular BCC).
• Subtype association: Associated with early nodular BCC.
• Size criterion: Encompasses less than 10% of the tumor's surface area (structures >10% are classified as ovoid nests).

4.2.3 Large Blue-Gray Ovoid Nests

• Morphology: Nonaggregated, round to oval structures, usually situated in a relatively hypopigmented background. Despite initially being described as "blue-gray," they can be brown or even pink in color.
• Size criterion: Encompasses >10% of the lesion's surface area (structures smaller than this threshold are classified as nonaggregated globules).
• Size continuum: There is a continuum from large ovoid nests to smaller globules with no clear-cut separation points. Since both ovoid nests and nonaggregated globules share the same histopathologic correlation (nodular BCC tumor islands), they may reasonably be considered one entity.
• Histopathologic correlation: Nodular BCC tumor islands.
• Sensitivity/Specificity: 55% sensitivity; 97% specificity vs. melanoma, 99% vs. benign pigmented lesions.

4.2.4 Leaf-Like Structures (Maple-Leaf Structures)

• Morphology: Linear to bulbous projections that converge toward an off-center base. Usually brown to gray-blue in color.
• Histopathologic correlation: Pigmented BCC tumor budding from the epidermis.
• Subtype association: Superficial BCC (in the absence of ovoid nests, arborizing vessels, and ulceration, leaf-like structures are highly suggestive -- if not diagnostic -- of pigmented superficial BCC).
• Specificity: 100% for BCC diagnosis.
• Key distinction from melanocytic streaks:
• Melanocytic streaks: Sharply focused extensions at the lesion's perimeter; radiate outward toward normal skin, away from the main tumor mass; converge toward the geometric center of the lesion, which is often hyperpigmented with a blue-white veil.
• BCC leaf-like structures: Broader and less sharply in focus; do not necessarily locate at the perimeter; do not always radiate away from the tumor mass; individual projections can point toward the lesion's center; converge at an off-center base (not the geometric center); the geometric center of BCCs displaying leaf-like areas is often hypopigmented and relatively structureless.

4.2.5 Spoke-Wheel Structures / Concentric Structures (Concentric Globules)

• Morphology (spoke-wheel): Radial projections converging at a central base/hub. The central hub is usually darker (brown, blue, or black) compared with the radial projections (brown, blue, or gray).
• Morphology (concentric structures): Variant form where radial projections are not well-defined, manifesting as brownish globules with a central darker hub.
• Histopathologic correlation: Pigmented BCC tumor islands budding off the epidermis.
• Subtype association: Superficial BCC.
• Specificity: 100% for BCC diagnosis.
• Overlap: Significant morphologic overlap exists between leaf-like structures, spoke-wheel structures, and concentric globules -- all correspond to pigmented superficial BCC.

Diagnostic Rule: In the absence of ovoid nests, arborizing vessels, and ulceration, the presence of leaf-like structures, spoke-wheel structures, and/or concentric globules is highly suggestive, if not diagnostic, of pigmented superficial BCC with a specificity of 100%.

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Check Your Understanding

What are the most common dermoscopic structures seen in basal cell carcinoma?

The most common structures include arborizing (tree-like branching) vessels, blue-gray ovoid nests, leaf-like areas, spoke-wheel structures, and ulceration. Arborizing vessels are the single most characteristic feature of nodular BCC.

Key Takeaways

• Classic pigmented BCC criteria (Menzies et al.) require absence of a pigment network plus at least one of six positive features: arborizing vessels, leaf-like areas, large blue-gray ovoid nests, spoke-wheel areas, ulceration, or multiple blue-gray globules/dots.
• Arborizing vessels are the single most specific dermoscopic feature for BCC and correspond to dilated arterioles feeding the tumor.
• Blue-gray ovoid nests and leaf-like areas represent pigmented BCC tumor islands at the DEJ and are best seen in the superficial component.

4.3.1 Arborizing Telangiectasia

• Morphology: Large-caliber vessels that branch into smaller-caliber vessels in a "tree-like" or "arborizing" pattern. Sharply in focus, bright red, and appear to traverse the skin superficially.
• Histopathologic correlation: Neoangiogenic vessels surrounding dermal BCC tumor islands.
• Subtype association: Nodular BCC -- the most specific vessel morphology for this subtype.
• Sensitivity/Specificity: 52% sensitivity; 77% specificity vs. melanoma, 92% vs. benign pigmented lesions.

4.3.2 Short-Fine Telangiectasia

• Morphology: Very thin-caliber vessels with a linear undulating to branching morphology.
• Subtype association: Superficial BCC -- the most common vessels in this subtype.
• Variant of: Arborizing vessels (described by Altamura et al., 2010).
• Key differential: Short-fine telangiectasia can also be seen in amelanotic superficial spreading melanoma. However, almost all superficial BCCs displaying such vessels will also reveal shiny white blotches or strands under polarized light dermoscopy, whereas amelanotic superficial melanoma will typically show no shiny white structures or only short shiny white lines.
• Important caveat: Thin-caliber telangiectasias can also be seen in lichen planus-like keratosis (LPLK), which can be confused with superficial BCC.

4.3.3 Polymorphous Vessels (Anatomic Variant)

• Location specificity: BCCs on the lower extremity display a nondescript polymorphous vascular pattern rather than the classic arborizing or short-fine patterns.
• Morphology: Mix of hairpin, serpentine, and glomerular vessels.
• Clinical significance: Vessel morphology in BCCs on the legs cannot be reliably used for diagnosis; clinical context and other dermoscopic structures are essential.

4.3.4 Ulceration and Erosions

• Ulceration:

• Corresponds to full-thickness loss of the epidermis.

• Associated with nodular BCC.

• Appears as red to orange, moist to sero-crusted areas.

• Sensitivity/Specificity: 27% sensitivity; 87% specificity vs. melanoma, 97% vs. benign pigmented lesions.

• Multiple small erosions:

• Correspond to partial-thickness loss of the epidermis.

• Feature of superficial BCC.

• Appear as well-demarcated sero-crusted areas, 1 mm or less in diameter.

• Variant of ulceration (described by Altamura et al., 2010).

4.3.5 Shiny White Blotches and Strands (Chrysalis-Like Structures)

• Modality requirement: Seen ONLY with polarized light dermoscopy -- cannot be visualized with nonpolarized dermoscopy.
• Morphology:
• Blotches: Correspond histopathologically to "pools" of mucin.
• Strands: Correspond to altered stroma in BCC.
• Diagnostic significance: Can sometimes be the only structure visible within a BCC. One study showed that approximately 65% of nonpigmented BCCs lacked all diagnostic structures except for shiny white blotches and strands (Navarrete-Dechent et al., 2016).
• Sensitivity/Specificity: 30% sensitivity; 91% specificity.
• Differential from melanoma: In amelanotic superficial melanoma, shiny white structures are absent or only short shiny white lines are seen, whereas superficial BCC will show shiny white blotches or strands.

4.3.6 Multiple Aggregated Yellow-White (MAY) Globules

• Morphology: Multiple, aggregated, yellowish to whitish globules.
• Light modality: Visible in both polarized and nonpolarized light (distinguishing them from milia-like cysts, which are more conspicuous under nonpolarized dermoscopy).
• Histopathologic correlation: Calcifications within the BCC tumor.
• Sensitivity/Specificity: 21% sensitivity; 99% specificity.
• Subtype association:
• Found in >50% of infiltrative and morpheaform BCCs.
• Found in approximately 20% of nodular BCCs.
• Not found in superficial BCC.
• Presence indicates the BCC is of either the nodular or aggressive (infiltrative/morpheaform) subtype.

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Clinical Scenario

A 76-year-old man presents with a pearly, translucent nodule on the left nasal ala that has been slowly enlarging over 6 months. A central ulceration with hemorrhagic crust is visible clinically. Dermoscopy reveals large arborizing vessels with bright red color and sharp focus on a translucent background, blue-gray ovoid nests occupying approximately 15% of the lesion surface, and shiny white blotches and strands visible under polarized light. No pigment network is present.

What is your diagnosis and key dermoscopic findings?

Pigmented nodular basal cell carcinoma

This lesion demonstrates the classic dermoscopic criteria of BCC. Applying the Menzies diagnostic method: (1) the absence of a pigment network, plus (2) the presence of at least one of the six classic pigmented BCC structures (blue-gray ovoid nests) yields a sensitivity of 93% and specificity of 89-92%. The arborizing telangiectasia is the most specific vessel type for nodular BCC, created by neovascular vessels surrounding dermal tumor islands. The blue-gray ovoid nests correspond to large pigmented BCC tumor nodules in the dermis. Shiny white blotches and strands (polarized-light only) correspond to stromal alteration around BCC tumor islands and mucin collections. Ulceration indicates full-thickness epidermal loss, confirming a nonsuperficial subtype.

4.4.1 Nodular BCC

Predictive dermoscopic features:

• Arborizing telangiectasia (most specific vessel type)
• Large blue-gray ovoid nests
• Blue-gray nonaggregated globules (early nodular BCC)
• Ulceration (full-thickness epidermal loss)
• MAY globules (approximately 20% of cases)
• Shiny white blotches and strands (polarized light)

Clinical context: Typically a flesh-colored or translucent papule/nodule, may develop central ulceration. Arborizing vessels surround dermal tumor islands.

4.4.2 Superficial BCC

Predictive dermoscopic features:

• Short-fine telangiectasia (most common vessels)
• Leaf-like structures (100% specificity)
• Spoke-wheel structures / concentric globules (100% specificity)
• Multiple small erosions (partial-thickness, 1 mm or less)
• Multiple blue-gray in-focus dots (bird-shot scatter)
• Shiny white blotches and strands (polarized light)

Diagnostic rule: In the absence of ovoid nests, arborizing vessels, and ulceration, the presence of leaf-like structures, spoke-wheel/concentric structures, in-focus dots, short-fine telangiectasia, or multiple small erosions is highly suggestive of superficial BCC.

Clinical context: Typically an erythematous macule or thin plaque, often on the trunk. May be amenable to noninvasive treatment (topical imiquimod).

4.4.3 Infiltrative / Morpheaform BCC

Predictive dermoscopic features:

• MAY globules (found in >50% of cases -- highest prevalence among subtypes)
• Shiny white blotches and strands
• Possible arborizing or thin vessels
• Features of higher-risk subtype

Clinical context: Scar-like, ill-defined plaque. The presence of MAY globules suggests a higher-risk subtype and should influence management toward more aggressive surgical treatment.

4.4.4 Pigmented BCC

Dermoscopic features: Any subtype can be pigmented. Pigmented BCC combines the subtype-specific features above with the classic pigmented structures:

• Blue-gray ovoid nests
• Blue-gray nonaggregated globules
• Blue-gray dots
• Leaf-like structures
• Spoke-wheel / concentric structures

Diagnostic rule (Menzies method): Absence of pigment network + presence of at least one of the six classic BCC structures = sensitivity 93%, specificity 89-92% for pigmented BCC.

Treatment relevance: Pigmentation in a BCC portends a poor response to photodynamic therapy (PDT). Dermoscopy can reveal clinically undetectable pigmentation in approximately 30% of nonpigmented BCCs, enabling better patient selection for PDT.

4.4.5 Fibroepithelioma of Pinkus

Note: This rare BCC variant is mentioned in the broader literature but is not specifically detailed in Chapter 6b. It typically presents with fine arborizing vessels, white-to-pink structureless areas, and sometimes dotted vessels, overlapping with other BCC subtypes.

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Check Your Understanding

How does the dermoscopic appearance of superficial BCC differ from nodular BCC?

Superficial BCC typically shows short fine telangiectasias (not thick arborizing vessels), multiple small erosions, and shiny white-red structureless areas, often with a background of diffuse erythema. Nodular BCC, in contrast, shows large arborizing vessels, blue-gray ovoid nests, and may show ulceration. The vascular pattern difference is the most distinguishing feature.

Key Takeaways

• Blue-gray globules and dots scattered in a birdshot pattern are characteristic of superficial BCC and correspond to small nests of pigmented basaloid cells.
• Shiny white blotches and strands are highly specific for BCC (not collagen-related like shiny white lines) and represent mucin and BCC matrix.
• Ulceration in BCC ranges from small erosions (superficial BCC) to large central ulcers (nodular BCC) and correlates with tumor aggressiveness.

Nonpigmented BCCs present a diagnostic challenge because they lack the highly specific pigmented structures. Key diagnostic features:

1. Shiny white blotches and strands (polarized light only) -- present in the majority and may be the sole diagnostic criterion in approximately 65% of nonpigmented BCCs.
2. Arborizing telangiectasia -- the most recognizable vascular pattern pointing to nodular BCC.
3. Short-fine telangiectasia -- suggests superficial BCC; differentiate from amelanotic melanoma by accompanying shiny white blotches/strands.
4. MAY globules -- associated with nodular or aggressive subtypes.
5. Ulceration/erosions -- ulceration suggests nodular, small erosions suggest superficial BCC.
6. Polymorphous vessels (lower extremity) -- nonspecific; require clinical correlation.

Clinical Pearl: When evaluating a pink/nonpigmented lesion, always examine with polarized light dermoscopy to detect shiny white blotches and strands, which may be the only clue to the diagnosis of BCC.

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STEP 1: Is a pigment network present?
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 +-- YES --> Not BCC (evaluate for melanocytic lesion)
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 +-- NO --> Proceed to Step 2

STEP 2: Are any BCC-specific structures present?
 |
 Classic criteria (Menzies):
 | - Blue-gray ovoid nests
 | - Blue-gray nonaggregated globules
 | - Leaf-like structures
 | - Spoke-wheel / concentric structures
 | - Arborizing telangiectasia
 | - Ulceration
 |
 Variant/Supplementary criteria:
 | - In-focus blue-gray dots
 | - Short-fine telangiectasia
 | - Multiple small erosions
 | - Shiny white blotches and strands (polarized)
 | - MAY globules
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 +-- ONE OR MORE PRESENT --> Diagnosis of BCC
 | |
 | +-- Proceed to Step 3 (Subtype Prediction)
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 +-- NONE PRESENT --> Consider other diagnoses

STEP 3: Subtype Prediction
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 +-- Leaf-like structures, spoke-wheel/concentric structures
 | short-fine telangiectasia, multiple small erosions
 | in-focus dots (WITHOUT ovoid nests, arborizing vessels
 | or ulceration)
 | --> SUPERFICIAL BCC
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 +-- Arborizing vessels, blue-gray ovoid nests, ulceration
 | --> NODULAR BCC
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 +-- MAY globules (especially >50% prevalence)
 | --> INFILTRATIVE / MORPHEAFORM BCC (higher risk)
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 +-- Any subtype + pigmented structures
 --> PIGMENTED variant of that subtype

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Check Your Understanding

What dermoscopic features suggest a pigmented BCC, and how can it be distinguished from melanoma?

Pigmented BCC shows the classic BCC structures (arborizing vessels, leaf-like areas, spoke-wheel structures) combined with pigmentation such as blue-gray ovoid nests and globules. Unlike melanoma, pigmented BCC lacks a pigment network and shows the characteristic BCC vascular pattern. The presence of arborizing vessels with pigmented structures points to BCC rather than melanoma.

Clinical Scenario

A 62-year-old woman presents with a 15 mm erythematous, slightly scaly thin plaque on the upper trunk that has been present for approximately one year. Dermoscopy reveals short-fine telangiectasia, multiple small erosions (partial-thickness, less than 1 mm each), and leaf-like structures at the periphery with brown-to-gray radial projections connected to an off-center base. Blue-gray in-focus dots are scattered in a bird-shot pattern. No arborizing vessels, ovoid nests, or ulceration is seen.

What is your diagnosis and key dermoscopic findings?

Superficial basal cell carcinoma

The diagnostic rule for superficial BCC applies: in the absence of ovoid nests, arborizing vessels, and ulceration, the presence of leaf-like structures, in-focus dots, short-fine telangiectasia, and multiple small erosions is highly suggestive of the superficial subtype. Leaf-like structures have 100% specificity for BCC and correspond to aggregates of pigmented BCC nests at the DEJ and papillary dermis. The small erosions represent partial-thickness epidermal loss characteristic of superficial BCC. This subtype distinction matters clinically because superficial BCC on the trunk may be amenable to noninvasive treatment with topical imiquimod.

Key Takeaways

• Nonpigmented BCC relies on vessel morphology for diagnosis: arborizing vessels (nodular), short fine telangiectasias (superficial), and scattered unfocused vessels (morpheaform).
• Superficial BCC shows multiple small erosions, shiny white-red structureless areas, and short fine telangiectasias, distinct from nodular BCC patterns.
• Morpheaform/infiltrative BCC is the most difficult subtype to diagnose dermoscopically, often showing only subtle shiny white areas and scattered unfocused vessels.

Dermoscopy assists in assessing BCC margins for treatment planning:

• Superficial BCC: Leaf-like structures, spoke-wheel/concentric structures, and in-focus dots at the lesion periphery help define lateral extent.
• Nodular BCC: Arborizing vessels and ovoid nests help delineate the tumor boundary.
• Treatment monitoring: After noninvasive treatment (imiquimod, PDT), dermoscopy can detect residual or recurrent BCC:
• Disappearance of all pre-treatment dermoscopic criteria predicts BCC clearance.
• Persistence or re-appearance of BCC criteria suggests persistence or recurrence.

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BCC vs. Melanoma

• BCC lacks a pigment network; melanoma typically has an atypical network.
• Leaf-like structures and spoke-wheel structures have 100% specificity for BCC (not seen in melanoma).
• Blue-gray globules in BCC are nonaggregated and blue-gray; in melanoma, globules are aggregated and brown-to-black.
• Leaf-like structures converge at an off-center base; melanocytic streaks converge toward the geometric center and radiate outward.
• BCCs with leaf-like areas have a hypopigmented, structureless center; melanomas often have a hyperpigmented center with blue-white veil.

BCC vs. Intradermal Nevus (Miescher Type)

• Dome-shaped intradermal nevi (IDN) can also display arborizing vessels, mimicking nodular BCC.
• Distinguishing features: IDN typically shows accompanying globules and lacks other BCC criteria (ovoid nests, ulceration, shiny white blotches).
• Biopsy may be required to rule out BCC definitively.

BCC vs. Lichen Planus-Like Keratosis (LPLK)

• Pinkish macular LPLK can display fine-caliber telangiectasias, mimicking superficial BCC.
• Distinguishing features: LPLK typically shows granularity (peppering/regression structures) rather than BCC-specific structures.
• Biopsy is not uncommon in practice to rule out BCC.

BCC vs. Sebaceous Hyperplasia

• Both can appear as yellowish papules on the face.
• Sebaceous hyperplasia: Crown vessels (branching vessels surrounding a central umbilication), yellowish lobules, no BCC-specific structures.
• BCC: Arborizing vessels, possible MAY globules or shiny white structures, no central umbilication with crown vessels.

BCC vs. Trichoblastoma

• Trichoblastoma can share several features with BCC including blue-gray structures and arborizing vessels.
• Distinguishing features: Trichoblastoma is less likely to show ulceration or shiny white blotches/strands; clinical context (location, history) assists differentiation.
• Biopsy is often required for definitive diagnosis.

BCC vs. Amelanotic Superficial Spreading Melanoma

• Both can display thin linear vessels.
• Key differentiator: Almost all superficial BCCs with short-fine telangiectasia will also reveal shiny white blotches or strands under polarized dermoscopy, whereas amelanotic melanoma will usually reveal no shiny white structures or only short shiny white lines.

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Key Takeaways

• BCC must be differentiated from melanoma (pigmented variants), sebaceous hyperplasia (crown vessels vs arborizing), and trichoepithelioma (similar but lacks ulceration and arborizing vessels).
• Dermoscopic margin assessment before surgery can improve complete excision rates, particularly for superficial and morpheaform subtypes.
• When BCC features overlap with melanoma (blue-gray structures, shiny white lines), the absence of a pigment network and presence of arborizing vessels favor BCC.