Oncocytoma of Kidney. Morphologic Variability of 102Cases

Overview

From the collection of 2500 cases of renal epithelial tumors in our files, 102 renal oncocytomaswere analyzed for size, multifocality and a morphologic spectrum of the growth pattern. The sizeof the tumors ranged from 1.5 to 13 cm in diameter, with a mean of 6.3 cm. Three cases weremultifocal, four cases were combined with another primary renal tumor (1x angiomyolipoma, 1xconventional renal carcinoma, 2x papillary renal cell carcinoma). A central fibrosis or a scar wasnoted in 13 cases, and there was a gross area of hemorrhage in 11 cases. In 4 cases extensivenecroses were recognized.Histologically, an alveolar pattern was noted in 70 cases. A tubular pattern was revealed in 31cases and an unusual tubopapillar („glomeruloid“) pattern was noted in one case. Foci of atypicalnuclei were identified in 58 cases. In 4 oncocytomas broad areas of clearance of the oncocyteswere found. Psammoma bodies were recognized in 9 tumors and foci of ossification were presentin 4 cases. Intracellular and extracellular hyaline globules were noted in two cases.Renal oncocytoma has a variable morphologic spectrum, and its diagnosis should be based on ananalysis of structural and cytologic features. Differential diagnosis of renal oncocytomas withvarious tumors of the kidney which contain granular cytoplasm is discussed. These tumors withgranular cytoplasm include conventional renal cell carcinomas, chromophobe cell carcinomas,and rare examples of papillary renal carcinomas.

Key words:
renal oncocytoma - kidneys - renal tumors - renal carcinoma