Atypical melanocytic lesions of the thigh with spitzoid and dysplastic features: a clinicopathologic study of 29 cases.

Melanocytic nevi in certain anatomic locations can display unusual histopathologic features potentially creating diagnostic uncertainty. Benign melanocytic nevi in sites such as acral, genital, and flexural areas may show unusual architecture and cytologic atypia, which can mimic dysplastic nevi and, sometimes, melanoma. Twenty-nine benign melanocytic skin lesions were identified in the thigh of 26 women and 3 men who showed atypical histologic features, including both dysplastic and spitzoid features. All lesions measured less than 1 cm in diameter. Eighteen cases showed features of compound nevi, and 11 were junctional. In all cases, the lesions displayed spitzoid features including large epithelioid and/or spindle cells, some melanocytes with ganglion-like cytomorphology, and focal suprabasilar upward migration. All cases showed dysplastic features. Clinical follow-up was available in 26 patients; no recurrences or metastases were observed. The demographic features and the anatomical sites of these melanocytic nevi appear to be reproducible, and in the assessment of histologically difficult cases, these data are helpful. It is our opinion that the malignant potential of these lesions with hybrid patterns (spitzoid/dysplastic) has yet to be determined, and although we favor these lesions to be benign, longer follow-up may yield a more complete understanding of their biologic potential.

CD8-positive primary cutaneous anaplastic large T-cell lymphoma (PCALCL): case report and review of this unusual variant of PCALCL.

Primary cutaneous anaplastic large T-cell lymphoma (PCALCL) is a well-defined CD30-positive lymphoproliferative disorder with relatively good prognosis and response to treatment. We describe a case of PCALCL expressing CD8. The patient is a 57-year-old man that clinically presented with an ulcerated nodule in his left middle finger. Histopathologic sections showed an ulcerated epidermis with a diffuse lymphocytic infiltrate in the superficial dermis with focal epidermotropism. The large cohesive atypical cells were admixed with a reactive infiltrate composed of neutrophils, eosinophils, and small lymphocytes. Immunohistochemical studies showed the tumor cells to be strongly positive for CD8, CD30, and TIA-1, focally positive for CD3, and negative for CD4, CD20, CD56, Anaplastic Lymphoma Kinase (ALK-1), and HSV. Epstein-Barr virus by in situ hybridization was negative. The diagnosis of a CD8+ PCALCL was confirmed. There is limited precedent literature regarding CD8-positive PCALCL and this case falls within the clinical and histopathologic spectrum of CD30+ lymphoproliferative disorders. CD8/CD30 coexpression is rare in PCALCL and may have important clinical and prognostic implications. To the best of our knowledge there are only 4 previously reported cases describing similar findings.