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| Fig. 41.3 Spitz nevus. Typical red papule on the cheek of a young child. Because of their red color, they are clinically often mistaken for vascular neoplasms. (Courtesy of the William L. Weston, M.D. Collection.) |
A Spitz nevus is a benign melanocytic nevus named in honor of Dr. Sophie Spitz, who initially described this lesion as a
benign juvenile melanoma. These most commonly occur in children but may occur at any age. Spitz nevi are most commonly acquired but as many as 7% may be congenital. The lesion usually presents as a small, pink papule or nodule on the face or lower extremities (Fig. 41-3). Histologically, it is composed of nevus cells that are pleomorphic and cytologically atypical; these cells typically demonstrate a spindle or epithelioid appearance that shares many of the histologic characteristics found in melanoma. The histologic differentiation of Spitz nevus from malignant melanoma is one of the most difficult challenges in dermatopathology and, in some cases, the biologic behavior cannot be predicted using current criteria. It is noteworthy that, to date, no B-Raf mutations have been detected in Spitz nevi, in contrast to common acquired melanocytic nevi. A small subset of Spitz nevi demonstrate
H-Ras mutations.
Sulit DJ, Guariano RA, Krivda S: Classic and atypical Spitz nevi: review of the literature,
Cutis 79:141–146, 2007.
Takata M., Saida, T: Genetic alterations in melanocytic tumors,
J Dermatol Sci 43:1–10, 2006.
