Abstract

Introduction The diagnosis of renal cell carcinoma portends a poor prognosis. It accounts for 2-3% of all adult solid tumors. The majority (60%) of cases are of clear cell type. Cutaneous metastases from internal organs, although rare, can signify a poor prognosis. In addition to malignant melanoma, cancers of lung, colon, ovary, and breast are associated with cutaneous metastasis. Patient History A 47-year-old man presented to the dermatologist with erythematous papules on the left anterior scalp and left cheek that have been progressively enlarging for the past 3 weeks. Confocal microscopy and later biopsy of both cutaneous lesions was performed. The patient had a history of renal cell carcinoma and was undergoing radiation therapy. To the authors’ knowledge, this is the first time the RCM features of RCC metastasis to the skin have been elucidated. Biopsy The lesion consisted of an intradermal nodule composed of clear cells in a glandular configuration with a prominent vascular stroma. Multiple erythrocytes were noted. Pancytokeratin, vimentin, and EMA stains were positive. CD10 was focally positive. Reflectance Confocal Microscopy The lesion showed a well-defined nodule in the dermis composed of epithelial cells distinct from surrounding keratinocytes. The reflectance confocal microscopy (RCM) features are suggestive of a metastatic tumor, as it lacks features of a squamous cell carcinoma, basal cell carcinoma, or a melanocytic tumor. Diagnosis A diagnosis of metastasis renal cell carcinoma with cutaneous lesions was established.

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