M 50, scalp nodule, history of renal cell carcinoma with single brain metastasis 5 yrs earlier.

    A 50-year-old man presented with a nodule on the scalp that had developed over the last few months. A 2 cm partially cystic dermal nodule on the scalp was thought to be a pilar cyst on clinical examination. The lesion was located within an old craniotomy scar. Past history revealed that the patient had renal cell carcinoma with a single metastatic nodule in the brain five years earlier. After undergoing a left nephrectomy, the brain nodule was initially treated by radiotherapy and subsequently by surgical resection 2 years later. Nineteen months after craniotomy the patient developed a scalp nodule within the craniotomy scar. There was no evidence of any other tumor. The excised scalp nodule on microscopic examination showed features of a renal cell carcinoma (Figs. 1 and 2) with polyhedral tumor cells in a glandular configuration with round or oval nuclei, prominent nucleoli, and granular or clear cytoplasm. The tumor cells showed positive immunostaining for vimentin, RCC (renal cell carcinoma) antibody (Fig. 3) and AR (Androgen receptor). The patient remains free of recurrent tumor six months after the resection of the scalp lesion.

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