Robotic Excision and Pathologic Profiling of Nonfunctioning Juxtaglomerular Cell Tumor of the Kidney: First Reported Case From the Indian Subcontinent.

Juxtaglomerular cell tumor (JGCT), also known as reninoma, is an exceptionally rare benign renal neoplasm arising from modified smooth muscle cells of the afferent arteriole of the juxtaglomerular apparatus. The tumor classically presents in young patients with secondary hypertension due to autonomous renin secretion, hypokalemia, and hyperaldosteronism.  A 56-year-old asymptomatic female with known hypothyroidism was incidentally detected to have a right renal mass on a routine health check-up. Contrast-enhanced computed tomography (CECT) confirmed a 2.7 × 2.5 cm homogeneously enhancing medullary lesion in the inter and lower polar region of the right kidney with mass effect and calyceal splaying. She underwent robot-assisted right partial nephrectomy. Histopathology confirmed a juxtaglomerular cell tumor, limited to the kidney, with uninvolved margins. Immunohistochemistry showed diffuse positivity for vimentin, smooth muscle actin (SMA), caldesmon, and CD34. This case is atypical in its presentation - an older, asymptomatic, post-menopausal female without the classic triad of hypertension, hypokalemia, and elevated renin levels. Nephron-sparing surgery is the treatment of choice whenever feasible. A high index of suspicion and a characteristic immunohistochemistry (IHC) profile are essential for definitive diagnosis.