Sarcomatoid renal cell carcinoma with a chromophobe component producing beta-human chorionic gonadotropin

We report a case of sarcomatoid renal cell carcinoma with a chromophobe component showing significant elevation of beta‐human chorionic gonadotropin (β‐HCG) in the peripheral blood. A 35‐year‐old man was hospitalized because of a large tumor of the left kidney and elevated serum levels of β‐HCG. Extended nephrectomy was performed, after which the serum β‐HCG level decreased. However, 3 months later, masses were discovered in the left renal bed and in the lung in association with elevated serum levels of β‐HCG. The patient was rehospitalized and received combination therapy with interferon‐α and doxorubicin‐based multiple chemotherapy (cyclophosphamide, vincristine, doxorubicin, and dacarbazine). The recurrent mass responded extremely well to treatment, and β‐HCG normalized. However, the patient died 14 months after nephrectomy because of eventual resistance to chemotherapy. Sarcomatoid renal cell carcinoma containing β‐HCG positive cells were pathologically diagnosed with immunohistochemical staining in the left kidney. Sarcomatoid renal cell carcinoma is a variant of renal adenocarcinoma which has a poor prognosis. This patient had an extremely rare sarcomatoid renal cell carcinoma associated with serum levels of β‐HCG which were elevated and strongly correlated with morphologic cancer activity. β‐HCG might be a useful serum marker for detecting and monitoring this renal cell carcinoma.