A 15-year old previously healthy girl was found to have elevated blood pressure (150/110 mm. Hg) during a routine physical examination for sports. On questioning, she gave history of headaches of 7-10 days duration. Laboratory evaluation showed elevation of plasma renin activity lateralizing to the left kidney (right renal vein renin 11; left renal vein renin 23). An abdominal CT scan revealed a 3.0 cm mass in the periphery of the left kidney. Renal angiography was negative for renal arterial lesion. Left partial nephrectomy was performed.

The partial nephrectomy specimen shows a 2.0 cm diameter, well-circumscribed multinodular mass surrounded by a rim of uninvolved renal parenchyma (Fig. 3.1). The tumor cells are monomorphic and arranged in nodular aggregates, anastomosing cords, and trabecular structures (Fig. 3.2). The background stroma is collagenous or myxoid containing mast cells (Fig. 3.3) and chronic inflammatory cells. Vasculature is well-developed consisting of small venules, muscular arterioles, and delicate capillaries interposed between the tumor cells (Fig. 3.4). The tumor cells are sometimes arranged concentrically around small arterioles as seen here (Fig. 3.5). Electron microscopy shows rhomboid or trapezoid electron-dense membrane-bound granules within the cisterns of Golgi complex (Fig. 3.6).

The differential diagnostic considerations include Wilms' tumor (Fig. 3.7), Juxtaglomerular cell tumor (Fig. 3.8), Renal cell carcinoma (Fig. 3.9), and Hemangiopericytoma (Fig. 3.10).

Juxtaglomerular Cell Tumor

Key Features:

• A rare renal tumor of young adults
• Produces a clinical syndrome characterized by hypertension, elevated plasma renin activity, secondary hyperaldosteronism, and hypokalemia that is reversed by resection of the tumor
• Usually small, well-circumscribed and encapsulated tumor located peripherally in the cortex
• Composed of homogenous population of polygonal tumor cells arranged in sheets, anastomosing cords, or trabecular structures interspersed with delicate branching vessels and small arterioles
• Background consists of myxoid or collagenous stroma with numerous mast cells
• Cytoplasm contains granules that are PAS-positive, diastase-resistant, and show immunoreactivity for Renin
• Rhomboid, membrane-bound, electron-dense renin "protogranules" are diagnostic (Fig. 3.11)
• Biological behavior is benign; although complications of hypertension may prove to be lethal
• Treatment is by partial nephrectomy
• No reports of recurrence, metastases, or malignant transformation

Follow-up:The patient became normotensive following surgery. After a brief recovery period, she resumed her sports activities and has remained asymptomatic. At the last follow-up, 2 years after surgery, her blood pressure was normal and renal ultrasound showed normal kidneys with no evidence of recurrence.

Not Available