Fine-needle aspiration biopsy of chromophobe renal cell carcinoma and oncocytoma - Comparison of cytomorphologic features

BACKGROUND. Chromophobe renal cell carcinoma (ChRCC) is a distinct tumor wi th a prognosis intermediate between renal oncocytoma (RO) and clear cell re nal cell carcinoma. To our knowledge the cytologic features of only a limit ed number of ChRCC have been described to date. A retrospective review of t he cytomorphologic features of ChRCC and a comparison with RO was performed . METHODS, Fine-needle aspiration biopsies (FNABs) of six cases of histopatho logically proven ChRCC were reviewed. The material examined was comprised o f smears, cytospins, Thin Prep(R) Pap Test(TM) preparations, and cell block sections stained with Diff-Quik(R), Papanicolaou, and hematoxylin and eosi n. Six FNABs of ROs were examined similarly. The cytomorphology of each tum or was studied and particular attention was paid to features differentiatin g the two entities. RESULTS. The characteristic cytomorphologic features of ChRCC (present in a ll cases) included round/oval, occasionally polygonal, moderately pleomorph ic large cells present singly and in small clusters. The abundant cytoplasm was variegated, ranging from dense to flocculent to vacuolated, with promi nent cytoplasmic membranes. The nuclei were large and hyperchromatic, with nuclear membrane irregularities and grooves present at least focally. Frequ ent binucleation was observed. Small nucleoli were present in many cells, b ut rarely prominent. In contrast, RO showed large cells with homogenous gra nular cytoplasm. The nuclei showed minimal to no nuclear membrane irregular ities, tiny nucleoli, mild pleomorphism, and only an occasional large, more hyperchromatic nucleus was observed. CONCLUSIONS. ChRCC has a distinct combination of cytomorphologic features. Careful attention to cytoplasmic and nuclear features allows for the distin ction between ChRCC and RO in cytologic preparations. (C) 1999 American Can cer Society.