Abstract:

Spitz melanoma of childhood is a rare and controversial variant of melanoma that generally has a favorable prognosis. Like atypical Spitz tumors, Spitz melanomas of childhood may metastasize to regional lymph nodes but appear to have a low mortality rate. We present a case of a 4-year-old girl with a rapidly growing, friable pink papule on the left posterior thigh. Histologic examination revealed an expansile and asymmetric proliferation of large epithelioid to spindled melanocytes with vesicular chromatin and prominent nucleoli. Marked cytologic pleomorphism, lack of maturation, and a high mitotic rate (up to 8/mm2) were appreciated. Immunohistochemistry revealed diffuse PRAME expression (4+) and loss of p16 in tumor cells. Fluorescence in situ hybridization (FISH) studies showed no copy number changes at the probed loci, including lack of CDKN2A homozygous deletion. However, subsequent single nucleotide pleomorphism (SNP) array demonstrated six copy number alterations, including a small homozygous deletion at 9p21 spanning CDKN2A locus. After extensive multidisciplinary discussion, sentinel lymph node biopsy was eventually performed in conjunction with wide local excision of the lesion, which revealed subcapsular and intraparenchymal deposits of atypical melanocytes morphologically identical to the primary tumor. Our case highlights several pitfalls in the classification of atypical Spitz tumors, particularly in young patients, and emphasizes the increased sensitivity of SNP array over FISH in identifying copy number alterations. Although our limited experience with Spitz melanoma of childhood suggests a favorable outcome despite the presence of aberrations seen in conventional melanomas, complete excision with clear margins and careful follow-up are indicated.

Financial Disclosure:
No current or relevant financial relationships exist.

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Jasmine Saleh, MD, MPH