September 2009 – Case of the Month #6
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We thank Dr. Mowafak Hamodat, Eastern Health of Newfoundland and Labrador, St. John’s, Canada, for contributing this case. We invite you to contribute a Case of the Month by sending microscopic images in JPG or GIF format, with a clinical history and any other images (gross, dermoscopy, immunostains, etc.) that may be helpful, to NatPernick@Hotmail.com. We will write the discussion (unless you want to), list you as the contributor, and send you a check for $35 (US) after we send out the case. Please only send cases with a definitive diagnosis.
Dermatology Case of the Month #6
Clinical history
A 24 year old woman had a 1 x 0.8 cm skin lesion with a central dark brown area, which was excised.
Micro images:
Low power
Medium power
High power
What is your diagnosis?
(scroll down to continue)
Diagnosis:
Pigmented epithelioid melanocytoma
Discussion
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”, epithelioid blue nevus of the Carney complex (myxomas, spotty skin pigmentation, endocrine overactivity and schwannomas, AJSP 1996;20:259), and some cases of cellular blue nevus (J Cutan Pathol 2009;36:439).
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 (Am J Surg Pathol 2009 Sep 21 [Epub ahead of print]). 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
DermatologyOutlines.com
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