Malignant juxtaglomerular cell tumor

Abstract

Juxtaglomerular cell tumors (JGCTs) are rare, typically benign neoplasms; only rare cases are clinically or histologically malignant. We herein report the histologic, immunophenotypic, and molecular features of a clinically unsuspected, diagnostically challenging case of malignant JGCT in a 23-year-old man. The diagnosis is confirmed with electron microscopy. The case is notable for its marked mitotic activity, which has not been previously reported in JGCTs, and novel finding of GATA3 immunohistochemical positivity.

Keywords: GATA3; Juxtaglomerular cell tumor; Kidney; Malignant; Renin.

Fig. 1

An axial computed tomography image with intravenous contrast demonstrating a solid mass (white arrow) in the lateral mid pole of the right kidney (A). Gross image of the tumor showing well-defined borders with a fleshy, hemorrhagic cut surface (B). Tumor borders are relatively sharp with occasional entrapped renal tubules at the periphery (C). The tumor is composed of ovoid to spindle cells with moderate nuclear pleomorphism, predominantly eosinophilic cytoplasm, and intimately associated with surrounding delicate vasculature. Mitotic figures are readily apparent (D).

Fig. 2

Immunohistochemical stains show tumor cells are diffusely positive for CD34 (A) and GATA3 (B). Electron microscopy shows tumor cells with cytoplasmic electron-dense rhomboid renin protogranule crystals (white arrows, inset) (C).