PIGMENTED EPITHELIOID MELANOCYTOMA (ANIMAL-TYPE MELANOMA)
By Gary M. White, MD
Pigmented epithelioid melanocytoma, aka animal-type melanoma, is an uncommon variant of melanoma characterized by a high rate of regional metastases, but limited evidence of distant metastases or disease-related death.
- Average age at diagnosis is 20-27 years depending upon the study.
- Regional metastasis (e.g. positive sentinel lymph node) occurs in about 47%.
- As of this writing, there has been only 1 documented case of a distant metastasis of PEM (to the liver). However, the overall survival is excellent with no cases of death attributed to PEM.
- Histologically PEM is indistinguishable from “epithelioid blue nevus,” which is associated with Carney complex. Tumors are composed of epithelioid and spindled melanocytes with heavy pigmentation.
The PEM typically presents as a solitary, darkly pigmented nodule on the scalp, face, neck, arms or trunk.
The standard treatment of melanoma with wide excision and sentinel lymph node biopsy is recommended. Further research is needed to determine if PEM should be treated in any way different from standard melanoma.
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