Fig. 4: Low-grade oncocytic tumor. | Modern Pathology

Fig. 4: Low-grade oncocytic tumor.

From: Novel, emerging and provisional renal entities: The Genitourinary Pathology Society (GUPS) update on renal neoplasia

Fig. 4

A common feature in this tumor  is edematous stroma with loosely connected cells that appear stretched out (A) rather than arranged in the typical round nests of oncocytoma. At high magnification, the cytology is usually bland and monotonous, with or without some perinuclear clearing (B). Diffuse CK7 labeling is typical (C), which differs from the rare positive cells usually seen in oncocytoma. KIT (CD117) staining (D) is typically negative, although mast cells may be positive, as in this example.

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