Telangiectatic Oncocytoma: Microscopically, there are variably-sized cystic spaces filled with blood or serosanguinous fluid that make up at least 50% of the tumor volume. The blood lakes are lined by typical oncocytic cells lacking cytologic atypia. There is no endothelial cell lining. Interstitial stromal hemorrhage is uncommon.
The differential diagnosis includes renal cell carcinomas with cystic change (clear cell, papillary and chromophobe types), tubulocystic carcinoma of the kidney, pigmented PEComa, metastatic melanoma, and benign lesions like cavernous hemangioma.
Same case as the previous image. Image courtesy of: Dr. Karen Pinto, Dept. of Pathology, Kuwait; Used with permission.
Reference: Xiao GQ, Ko HB, & Unger P. Telangiectatic oncocytoma: a previously undescribed variant of renal oncocytoma.