Figure 2

In renal cell carcinomas with angioleiomyoma-like stroma, small papillary tufts often protruded into the glandular structures (a). Some exhibited more complex branching papillary structures (b). A prominent layer of endothelial cells rimmed the tubules and nests, imparting a two-cell layer appearance (c). The endothelial nature of these cells was confirmed by immunohistochemical staining for CD34 (d). Similarly, a subset of tumors contained hemangioma-like proliferations of capillaries (e), highlighted by immunostaining for CD34 (f).