Pigmented epithelioid melanocytoma: Case report and update on the nomenclature of paediatric melanocytic tumours

A 13 year old girl presented with a six month history of a dark nodule arising from a congenital melanocytic naevus on her left buttock. Examination demonstrated an exophytic blue tumour with an eccentric black focus. Dermoscopy demonstrated homogenous blue and black pigmentation. Excision biopsy demonstrated a heavily pigmented spindled and epithelioid melanocytic tumour extending to the lower dermis. Prominent nuclear pleomorphism was observed with minimal mitotic activity and the absence of ulceration or lymphovascular invasion. The tumour was strongly positive for S100, Sox 10, HMB45, as well as P16 and P21. The clinical, dermoscopic and histological findings were in keeping with pigmented epithelioid melanocytoma (PEM).
PEM is a recently proposed term encompassing animal-type melanoma and atypical epithelioid blue naevus (of the Carney complex). They are low-grade melanocytic tumours typically arising in children and young adults. Loss of expression of the protein kinase A regulatory subunit type 1α is frequently observed. PEM has been reported to metastasise (typically via lymphotropic spread) but appears to follow an indolent clinical trajectory. Metastatic disease does not appear to portend a poorer prognosis. Given this entity was only described in 2004, longitudinal surveillance of patients is still required so that the natural course of this disease can be determined more definitively.

Dr. Victoria Snaidr

Department of Dermatology, Royal Prince Alfred Hospital, NSW

Victoria is a Dermatology Research Fellow at Royal Prince Alfred Hospital NSW, and a General Practitioner whose interests lie particularly with transplant dermatology medicine and rural and remote medicine.

Victoria has followed her interest in dermatology with research fellow roles in transplant dermatology at the Skin and Cancer Foundation Inc. Carlton, and as an Honorary Dermatology Registrar at the Royal Women’s Hospital, Melbourne.

Since moving to NSW from Victoria in 2016, Victoria has worked as an Honorary Dermatology HMO at Royal Prince Alfred Hospital. This has led her to her current role at RPA as Senior Research Fellow working on the ONTRANS (oral nicotinamide after transplant) study.

In her free time, Victoria enjoys baking (flat) cakes, redesigning (destroying) the garden, and completing her PhD (Projects half Done) in sewing and knitting.