Coexistent metastatic melanoma of the kidney with unknown primary and renal cell carcinoma, "Beyond the Abstract," by Melinda B. Chu, MD and John M. Richart, MD

BERKELEY, CA ( - Our patient presented with a symptom typical of renal cell carcinoma: hematuria. The identification of both malignant melanoma (MM) and renal cell carcinoma (RCC) in the kidney was unexpected and made this case unusual and noteworthy.

Renal metastases from any cancer are uncommon. The most common primary sites for renal metastases are: lymphomas and carcinomas of the lung, breast, and colon.[1]

Melanoma rarely metastasizes to the kidney. When it occurs, the majority of renal metastases are < 1 cm, asymptomatic, and identified at autopsy.[2, 3] In our case, the renal lesions were large. Ultrasound imaging of the right kidney revealed an 8.8×8.0×9.0 cm right lateral mass with peripheral hypervascularity and a 7.1×6.1×6.5 cm mass in the right mid-pole. The right lateral mass was positive for tumor markers consistent with primary renal cell carcinoma: CK7, CD10 and CK20. The large right medial mass was positive for Mart/Mel, a marker for malignant melanoma.

Malignant melanoma arises from uncontrolled proliferation of melanocytes and accounts for an estimated 2% of all cancers. It is known that patients with melanoma have a higher risk of developing cutaneous malignancies (both melanoma and non-melanoma skin cancers) as well as non-cutaneous malignancies.[4, 5, 6] However, the development of both MM and RCC in the same patient is a rare event.[7] Previous studies have showed rates of MM+RCC of 0.5% in patients with MM and 1% in patients with RCC.[8]

It is actually surprising that the coexistence of both tumors doesn’t occur more often since MM and RCC share a number of unique characteristics. Both cancers are relatively unresponsive to chemotherapy and radiotherapy, both may present with distant metastases early in disease course (as in this case), and lastly both cancers have antigenic properties. For this reason, we had considered treatment with high-dose interleukin-2 therapy, which is approved for both cancers. Unfortunately, the patient’s performance status precluded HD IL-2 as a treatment option.

Previous reports of coexistence of MM and RCC suggest that it is seen in the Caucasian population who are also at higher risk for developing cutaneous malignancies: those with lighter skin and eye color, red hair, sun-sensitivity, and a family history.8 Our patient, an African-American female patient was not of this demographic, did not have a family history of melanoma or renal cell carcinoma, nor was she immune-compromised. Thus, it is likely that our patient had heterogeneous etiologies leading to the development of melanoma and renal cell carcinoma.

Further reports of similar cases of coexistent melanoma and renal cell carcinoma may help to shed light on the etiology and pathogenesis of both conditions.


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Written by:
Melinda B. Chu, MDa and John M. Richart, MDb as part of Beyond the Abstract on This initiative offers a method of publishing for the professional urology community. Authors are given an opportunity to expand on the circumstances, limitations etc... of their research by referencing the published abstract.

aDepartment of Dermatology, St. Louis University, St Louis, Missouri USA
bDivision of Hematology and Oncology, St. Louis University, St Louis, Missouri USA

Coexistent metastatic melanoma of the kidney with unknown primary and renal cell carcinoma - Abstract

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