Variant chromophobe renal cell carcinoma - A morphology not recognized after routine fixation

Separation of renal cell tumors into different prognostic groups is an impe rative function of the diagnostic pathologist. Recently, chromophobe renal carcinoma has been described as a tumor that is morphologically distinct fr om onventional "clear cell" carcinoma and that has a low metastatic potenti al. Identification is based on routine light microscopic features and is co nfirmed by special stains, immunohistochemistry, and electron microscopy. W e present a variant of chromophobe renal carcinoma that did not show the ty pical cytomorphologic features on light microscopy after formaldehyde fixat ion. After fixation in Solufix (a commercial fixative), these features were recognized and the diagnosis was confirmed. The tumor also showed an unusu al form of calcification and psammoma body formation not previously recogni zed in chromophobe tumors. Molecular biological assessment was inconclusive , but excluded a chromosome 3p deletion usually found in conventional renal carcinoma. The use of a different primary fixative may provide a cost-effe ctive screening tool to detect variant renal tumors and may have important prognostic implications.