A man with a deltoid swelling and paraneoplastic erythrocytosis: case report.

Erythrocytosis is a well-known paraneoplastic syndrome occurring in 1% of cancer cases. Herein, we report a patient with a history of renal cell carcinoma (RCC) who developed a paraneoplastic erythrocytosis 3 months after curative nephrectomy. Concomitantly we documented the presence of a deltoid mass, highly suggestive for a muscle metastasis.