The juxtaglomerular cell tumor (JGCT) is a rare renal tumor characterized by excessive renin secretion causing intractable hypertension and hypokalemia. However, asymptomatic nonfunctioning JGCT is extremely rare. Here, we report a case of nonfunctioning JGCT in a 31-year-old woman. The patient presented with a left renal tumor without hypertension or hypokalemia. Under a clinical diagnosis of renal cell carcinoma, radical nephrectomy was performed. The tumor was located in the middle portion adjacent to the renal pelvis, measuring 2 cm in size. Pathologically, the tumor was composed of cuboidal cells forming a solid arrangement, immunohistochemically positive for renin. Based on these findings, the tumor was diagnosed as JGCT. In cases with hyperreninism, preoperative diagnosis of JGCT is straightforward but difficult in nonfunctioning case. Generally, JGCT presents a benign biological behavior. Therefore, we should take nonfunctioning JGCT into the differential diagnoses for renal tumors, especially in younger patients to avoid excessive surgery.
Juxtaglomerular cell tumor (JGCT), a neoplasm derived from the juxtaglomerular cell of the kidney, was first described by Robertoson et al. and Kihara et al. [
A 31-year-old woman was referred to our hospital with a left renal tumor incidentally detected during examination for left-side abdominal pain. She had no history of hypertension, and her blood pressure at presentation was 116/62 mmHg. All the laboratory data, including electrolyte levels, were within normal ranges. Unfortunately, preoperative plasma renin activity was not assayed. Unenhanced computed tomography (CT) revealed solitary well-circumscribed mass lesion measuring 2 cm with fine calcifications in the middle portion adjacent to the renal pelvis of the left kidney. Dynamic-enhanced CT demonstrated that the tumor was not enhanced in the corticomedullary (early) phase but enhanced in the excretory (late) phase (Figure
Enhanced CT showing the tumor (excretory phase) (arrow).
Grossly, the resected kidney contained an encapsulated yellowish white mass in the middle portion (Figure
Gross findings of the resected kidney. The tumor located in the middle portion and was well demarcated from the surrounding structures. The cut surface was white to tan in color.
Histologically, the tumor was composed of densely packed cells surrounding tubular spaces with cuboidal lining. The tumor cells were uniformly small in size, polygonal in shape, possessed small round nuclei, and were clear to eosinophilic cytoplasm. Their nuclei contained fine chromatin and inconspicuous nucleoli (Figure
Histological findings of the tumor. The tumor was composed of solid cell sheets containing tubular architectures.
Electron micrograph of a tumor cell. Rhomboidal crystalline bodies are observed in the cytoplasm of a tumor cell (arrow).
Immunohistochemical micrograph of the tumor. The majority of tumor cells were positive for renin, although the tubular lining was negative.
Based on these findings, the tumor was diagnosed as nonfunctioning JGCT. Postoperatively, the patient is doing well for more than 3 years of followup.
JGCT is a rare benign renal neoplasm, which mostly affects the younger females (second to third decades; mean age, 27 years old; male : female = 1 : 2). It is most frequently found during the examination for intractable hypertension.
On plain CT, JGCT usually appears as a unilateral well-circumscribed hypoattenuating cortical mass. At dynamic CT, the tumors are not enhanced in the arterial phase despite the profuse vascularity, possibly because of renin-induced vasoconstriction. The tumors show moderate enhancement during the delayed phase [
Grossly, the tumor is well circumscribed and firm in consistency, and the cut surface is yellowish to tan in color. Histologically, the tumor is composed of sheets, papillae, and trabeculae of uniform polygonal cells. Their nuclei are small with fine chromatin, and the cytoplasm is granular. Ultrastructurally, rhomboid renin protogranules are noted in the cytoplasm. Immunohistochemically, the tumor cells are positive for renin, but negative for epithelial markers. The candidates of differential diagnosis are oncocytoma, epithelioid angiomyolipoma, renal cell carcinoma, and mesenchymal tumors such as glomus tumor, solitary fibrous tumor, and hemangiopericytoma. Pathological diagnosis is usually straightforward, because of characteristic clinical presentation [
Because JGCT is mostly benign with an exceptional case causing metastasis [
Although the classical triad of JGCT is poorly controlled hypertension, elevated renin level, and renal mass, some cases had been reported which lacked hypertension and/or hypokalemia [
In cases of renal tumors especially in young females, even though no evidence of hyperreninism, JGCT should be included in the candidates of differential diagnosis, and excessive surgical treatment should be avoided to preserve the renal function and not to lose the kidney.