Difficulties in the diagnosis of spitzoid melanocytic lesions

Figures & data

Figure 1. Conventional Spitz nevus.

(A) Low power circumscription and symmetry with epidermal hyperplasia (40×). (B) Nests of epithelioid melanocytes are arranged vertically to the skin surface with ‘raining down’ appearance (100×). (C) Higher magnification shows epithelioid melanocytes, Kamino body and occasional pagetoid scattering (200×).

Figure 2. Pigmented spindle cell nevus.

(A) Circumscribed and symmetric lesion (40×). (B) Mostly junctional nevus composed of heavily pigmented spindled melanocytes (100×). (C) Heavily pigmented and spindled melanocytes without cytologic atypia (200×).

Figure 3. Desmoplastic Spitz nevus.

(A) Dermal-based lesion (40×). (B & C) Spindled and epithelioid melanocytes are arranged as fascicles or single units between sclerotic collagen bundles (100× and 200×, respectively). (D) Sclerotic collagen and epithelioid/spindled melanocytes (400×).

Figure 4. Angiomatoid Spitz nevus.

(A) Dermal-based lesion (40×). (B & C) Spindled and epithelioid melanocytes are set in a dense fibrous stroma, associated with prominent blood vessels (100× and 200×, respectively). (D) Epithelioid/spindled melanocytes and prominent vessels (400×).

Figure 5. Spitzoid dysplastic nevus.

(A) Small and circumscribed lesion (20×). (B & C) Epidermal hyperplasia and bridging of junctional nests (40× and 100×, respectively). (D) Horizontal bridging of junctional nests with concentric fibroplasia and mild dermal inflammation. The melanocytes are epithelioid. Kamino bodies are present (200×).

Figure 6. Atypical Spitz tumor.

(A) Dermal-based lesion with sheet-like growth pattern and incomplete maturation (40×). (B & C) Nests do not become smaller in deeper dermis (100× and 200×, respectively). (D) Melanocytes are epithelioid with nuclear pleomorphism (400×).

Figure 7. Spitzoid melanoma.

(A) Expansile dermal tumor with surface ulceration (20×). (B & C) Sheet-like growth pattern (40× and 100×, respectively). (D) Epithelioid melanocytes with nuclear pleomorphism, prominent nucleoli and mitoses (400×).

Table 1. Pertinent histopathologic findings of Spitz nevus, atypical Spitz tumor and spitzoid melanoma.

Feature	Spitz nevus	Atypical Spitz tumor	Spitzoid melanoma
Size	<1 cm	Often >1 cm	>1 cm
Symmetry	Symmetric	Often asymmetric	Asymmetric
Circumscription	Sharply demarcated	Variable, often not well circumscribed	Ill-defined
Ulceration	Rare	Variable, uncommon	Common
Cytologic atypia	Uncommon	Variably present	Common
Pleomorphism	Uniform, monotonous	Pleomorphic	Pleomorphic
Upward pagetoid spread	Occasional, nests > single cells	Common	Common
Kamino bodies	Frequent	Variable; may be poorly formed	Less common; poorly formed
Dermal cellularity	Variable	Prominent	Prominent
Sheet-like growth	Absent	Variable, common	Common
Expansile nodules	Absent	Variable, common	Common
Maturation	Common	Uncommon, variable	Uncommon or absent
Mitotic activity	Uncommon, superficial	Common, superficial and deep	Common, superficial and deep

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