Case 37 Male, 71 years. Pigmented skin tumour, backShow diagnosis & comments
Dermal hypermelanotic melanoma.
This example shows melanoma cells more akin to the usual melanoma types, but the heavy pigmentation and the entirely intradermal localization of this lesion are features of dermal hypermelanotic melanoma.
DERMAL HYPERMELANOTIC MELANOMA ('ANIMAL TYPE MELANOMA'; 'PIGMENT SYNTHESIZING MELANOMA')
- Dermal atypical melanocytic proliferation producing large amounts of melanin
- Scattered characteristic very large, pale vesicular nuclei with irregular macronucleoli
- Some mitotic activity (may be difficult to detect because of heavy pigmentation)
- Cases that metastasize are usually large, and metastases are often - but not always - restricted to the regional lymph nodes: overall, prognosis appears to be better than of melanoma NOS of similar thickness
- Occasionally, however, the tumour behaves aggressively, with widespread metastasis
- Some occur in conjunction with a naevus (as in this instance) or a melanoma of other histological type, such as superficial spreading melanoma NOS, or acral lentiginous melanoma
Within 5 years, there were two local recurrences with progressively extansive involvement of skin and undrelying tissues.