CHROMOPHOBE CELL-CARCINOMA OF THE KIDNEY - A CLINICOPATHOLOGICAL STUDY OF 21 CASES

The clinicopathologic features in a series of 21 chromophobe cell carc inomas are reviewed. Patients' ages ranged from 30 to 83 years (mean, 53 years), and the number of men and women was roughly equal. Major pr esenting complaints included hematuria, flank pain, and flank mass. Al l but two tumors were staged as tumor node metastasis (TNM) T(2)N(0)M( 0). Histologically, the carcinomas were composed of large cells with v ariably reticulated, translucent cytoplasm. The tumor cells could be d ivided into three types according to the extent and distribution of re ticulated cytoplasm. Ultrastructurally, these reticulated areas were c haracterized by the presence of large numbers of microvesicles, which appeared to be unique to chromophobe eel carcinomas because ultrastruc tural examination of 20 clear cell carcinomas and six granular eel car cinomas failed to reveal similar structures. The origin of the vesicle s appeared to be from saccular outpouchings from the outer mitochondri al membrane. Immunohistochemical studies revealed that all the tumors were variably positive for cytokeratins 8, 18, and 19, and epithelial membrane antigen but negative for vimentin. Flow cytometric DNA analys is of eight carcinomas revealed slightly hypodiploid cell populations in seven tumors. Of these, four also contained hyperdiploid cell popul ations. Follow-up (6-108 months) of 16 patients revealed all these pat ients to be alive and well. These findings further confirm the concept that chromophobe cell carcinoma is a special subtype of renal cell ca rcinoma in which the presence of microvesicles is a characteristic mor phologic feature. Furthermore, loss of chromosomal DNA may also be a f requent, perhaps unique, feature of chromophobe cell carcinoma.