In the older literature this lesion has previously been called epithelioid blue nevus, animal type melanoma, pigment synthesizing melanoma & equine melanoma. Indeed, my cases of so-called animal type melanoma were re-classified as pigmented epithelioid melanocytoma during the preparation of the seminal paper on the topic by Zembowicz & Carney.

Clinical features

•Most common in the 2^nd-4^th decades but may present in infants & children

•M=F

•No site predilection

•1.0 cm or larger brown, blue black or black nodules

•More commonly sporadic

•Less often form part of Carney complex

•Sentinel node +ve in 41%

•Very rare distant metastases although the outcome is generally favorable

Histological features, immunohistochemistry & molecular changes

•Dermal of less often compound

•Wedge shape or less often plaque like silhouette

•Commonly associated with marked acanthosis/pseudoepitheliomatous hyperplasia although much less commonly, the epidermis is strteched over the lesion

•Sometimes presents as a combined lesion- banal or Spitzoid

•Composed of an admixture of large epithelioid melanocytes with vesicular nuclei containing a very prominent nucleolus (fried egg cells), spindle cells, dendritic cells & melanophages

•The epithelioid cells are typically very uniform

•Few mitoses

•Perineural infiltration sometimes evident

•Absent necrosis & lymphovascular invasion

•Variable molecular changes including fusions in PRKCA), mutations in PRKAR1A & mutations in PRKAR1A and BRAF (in combined lesions)

•S100, SOX10, HMB45 & Melan-A +ve

•PRKAR1A –ve except for tumors associated with PRKCA fusions