Extracellular matrix globules in renal oncocytoma

Extracellular hyaline globules resulting from abnormal accumulation of matr ix components have been described in several pathological conditions, inclu ding renal tumors. We studied 16 renal oncocytomas and observed these bodie s in 11 of them. In these tumors, they showed a homogeneous texture as well as roundish, smooth contours, and were easily detected in hematoxylin-eosi n sections in five cases. PAS staining greatly facilitated the identificati on of globules in the remaining six cases, where they were fewer in number. Immunohistochemically, they appeared to be composed primarily of basement membrane material, being strongly reactive to antibodies for type IV collag en, laminin, and heparan sulphate proteoglycan. In addition, a weak immunor eactivity for type I and type III collagen, and fibronectin was observed in some cases, whereas no globule stained for tenascin. We also analyzed 89 r enal cell carcinomas, and found somewhat similar bodies in 10 of them. Howe ver, they were more scanty in the latter tumors, and displayed a more irreg ular configuration with granular or smudged contours. We conclude that, alt hough the mere presence of extracellular hyaline globules does not justify a distinction between renal oncocytoma and renal cell carcinoma, the detect ion of a large number of well-demarcated, roundish extracellular bodies wit h smooth contours suggests renal oncocytoma.