Spitz nevus arising in the eyelid of a teenager

A 16-year-old boy developed over a 2-month interval a lightly pigmented left upper eyelid lesion measuring 1.5 mm in greatest diameter that, when excised, microscopically was hypercellular and composed almost exclusively of nonpigmented epithelioid cells that created florid, large intraepidermal junctional nests and sheets and nests of subepidermal cells. The diagnosis was a Spitz nevus. HMB-45, MART-1, and microphthalmia-associated transcription factor were all positive and established the melanocytic nature of the benign tumor. The Ki-67 proliferation index (5%) and 2 mitoses/mm2 were both low; p16 protein was immunohistochemically identified in the nevoid cells. We review the clinical, histopathologic, and other immunohistochemical features of this entity and provide a brief differential diagnosis (including separation from a Spitzoid melanoma). This is only the third eyelid Spitz nevus reported in the literature and is the most fully characterized immunohistochemically. At their present stage of development, contemporary immunohistochemical biomarkers, while providing supplemental information, nonetheless remain less than definitive in terms of reliably distinguishing benign from malignant Spitz lesions.