RESUMO
Although prostate cancer is among the most frequent malignancies in the elderly, this tumor may be under-reported, and it seems that its socioeconomic burden is not well-estimated. Chronic urinary obstruction caused by the cancer may cause renal failure, with hemorrhagic tendency, neurologic disturbances, cutaneous disorders, and diverse fingernail changes. Black or brown nail pigmentation has been associated with benign and malignant conditions, including antineoplastic drugs' side effects, subungual metastases, and melanoma. Metastasis of fingernail melanoma can affect lymph nodes from the wrist to elbow and axillary regions. Coexistent melanonychia and wrist lump, mimicking melanoma with sentinel lymph node is reported. It is recommended to consider the differential diagnosis of nail changes due to chronic renal failure.