Coexistent malignant melanoma and renal cell carcinoma.

Patients with malignant melanoma are at an increased risk of developing subsequent primary melanomas and also nonmelanoma cutaneous cancers. Several studies have reported an association between malignant melanoma and breast cancer, bladder cancer, colorectal cancer, neuroectodermal tumours, non-Hodgkin's lymphoma, leukaemia and renal cell carcinoma. We report a case series of patients with a diagnosis of malignant melanoma who also developed a renal mass. In two of these cases, the renal mass became apparent on diagnostic imaging as part of the staging investigations at the time of initial diagnosis of the malignant melanoma. In both of these cases, biopsy of the renal mass confirmed the presence of a separate primary renal cell carcinoma which had presented concurrently with the malignant melanoma. A third case presented with bone metastases ten years after excision of a thin melanoma. Further imaging revealed pulmonary metastases and a renal mass, biopsy of which confirmed renal cell carcinoma. In contrast, a fourth patient underwent a right nephrectomy for a renal mass having presented with abdominal discomfort. The histology of this lesion was in keeping with metastatic melanoma, and the patient's past history included a diagnosis of ocular melanoma eight years prior to the development of metastatic disease in the right kidney. Survival rates for patients with many types of malignant disease are improving, and there have been significant advances in clinical imaging techniques. Consequently the development and detection of a second primary cancer, either presenting concurrently or on subsequent follow-up, is likely to be increasingly observed. The series of patients reported here highlights the importance of a diagnostic biopsy in patients with malignant melanoma who develop a renal mass in order to establish a diagnosis and to plan optimal treatment.