Mesoblastic Nephroma : Microscopic Features
Microscopic Features: Mesoblastic nephroma is well-circumscribed and unencapsulated tumor. Three histologic variants have been described - classic (25%), cellular (65%), and mixed (10%). The classic variant (shown here) is variably cellular and consists of intersecting fascicles of bland spindle cells with tapered nuclei and eosinophilic cytoplasm. The appearance resembles uterine leiomyomas or infantile fibromatosis. There is no cellular atypia or increased mitotic activity. The stroma shows variable amounts collagen deposition.