20 March 2008 – Case of the Week #113
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We thank Dr. Mowafak Hamodat, Eastern Health of Newfoundland and Labrador, St. John’s, Canada for contributing this case. To contribute a Case of the Week, email [email protected] with the clinical history, your diagnosis and microscopic images in JPG, GIF or TIFF format (send as attachments, we will shrink if necessary). Please include any other images (gross, immunostains, etc.) that may be helpful or interesting. We will write the discussion (unless you want to), list you as the contributor, and send you $35 (US dollars) for your time after we send out the case. Please only send cases with a definitive diagnosis, and preferably that are out of the ordinary.
Case of the Week #113
A 24 year old woman had a 1 x 0.8 cm skin lesion with a central dark brown area, which was excised.
What is your diagnosis?
Combined dermal / pigmented epithelioid melanocytoma
The diagnosis was confirmed by Dr. M. Mihm of Harvard Medical School.
Pigmented epithelioid melanocytoma is a low grade variant of melanoma first described under this name in 2004 (AJSP 2004;28:31). It includes lesions previously described as “animal-type melanoma” and epithelioid blue nevus of the Carney complex (myxomas, spotty skin pigmentation, endocrine overactivity and schwannomas, AJSP 1996;20:259).
The median patient age is 27 years, with a wide range. The extremities are the most common site, although numerous sites are affected. The tumor does not appear to be related to sun exposure. Clinically, the tumor resembles a combined nevus (gross image of other cases #1; #2). The tumor consists of heavily pigmented epithelioid or spindled melanocytes in the deep dermis. There is variable atypia, but no consistent high grade features. There may be ulceration, a combined nevus or rarely necrosis. Nodal metastases are found in 46% of cases, but death from disease is rare. Recommended treatment is sentinel lymph node sampling and conservative re-excision.
These tumors are associated with loss of the protein kinase A regulatory subunit type 1alpha (R1alpha), coded by the PRKAR1A gene, which is lost in both sporadic cases and patients with Carney complex (AJSP 2007;31:1764).
Differential diagnosis includes blue nevus (no pigmented and epithelioid cells) and nodular melanosis (pigmented cells are actually pigment laden macrophages).
Nat Pernick, M.D., President
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