Juxtaglomerular cell tumor: a case report

Abstract

Introduction

The tumor produces an excessive amount of renin resulting in secondary hyperaldosteronism, thereby causing hypertension with hypokalemia. The authors describe a case of reninoma in a young man, who presented with malignant hypertension.

Case presentation

A 35-year-old African male patient referred to our institution, presenting with severe hypertension for 4 years. Renal magnetic resonance imaging showed a solid 9-mm lesion in the right upper pole cortex with high signal intensity on diffusion-weighted imaging, isointense on T2, and enhanced after contrast injection. The patient underwent an open right partial nephrectomy. The diagnosis of reninomas was confirmed by histopathological examination.

Conclusion

Nephron-sparing surgery should be considered in patients with juxtaglomerular tumors. This technique allows prompt recovery with the preservation of significant renal function.

Introduction

Reninomas, or juxtaglomerular cell tumors (JGCTs), are rare renal tumors responsible for secondary hypertension [1]. Diagnosis is challenging owing to often nonspecific clinical manifestations. Through this case, we synthesize the clinical characteristics, laboratory data, and therapeutic approaches related to JGCTs.

Case presentation

A 35-year-old African male patient, smoker, without comorbidities, referred to our institution owing to severe hypertension for 4 years. Pulsating headaches occasionally accompanied his hypertension. The patient reported no significant family history of hypertension, renal tumors, or endocrine disorders. He had no nocturia, polydipsia, sweating, flushing, visual disturbance, or any neurological symptoms. He reported hematuria evolving for 8 months, and right lumbar pain without fever. Clinical examination revealed a body mass index (BMI) of 29 kg/m², mild right lumbar tenderness, and a palpable mass. The general examination found a blood pressure of 210/10 mmHg and a pulse of 100 bpm. The physical examination found a palpable mass in the right lumbar fossa, no varicocele, and no low limb edema. The urine cytobacteriological examination was negative. He had a hemoglobin level of 13.6 g/dl, a calcium level of 2.23 mmol/l, and a creatinine level of 7 mg/l. The results of a complete blood count and plasma levels of fasting glucose, cholesterol, sodium, and phosphorus were unremarkable, except for hypokalemia (2.8 mmol/L). The 24-h urine sodium and potassium output were 115.6 mmol and 44.2 mmol, respectively. A random plasma renin activity (PRA) was markedly increased (11.3 ng/mL/hr); however, serum aldosterone level was normal (134 pg/mL). The diurnal rhythm of serum cortisol was preserved, with a level of 16.9 μg/dL at 8:00 a.m. and 5.6 μg/dL at 4:00 p.m. The 24-h urinary vanillylmandelic acid was 2.8 mg. The computed tomography angiogram of the abdomen was normal. Renal magnetic resonance imaging (MRI) showed a solid 9-mm lesion in the right upper pole cortex. This lesion exhibited high signal intensity on diffusion-weighted imaging and was isointense on T2 and T1 sequences. It enhanced after contrast injection, and the integrity of the peri- and para-renal fat was maintained, which is highly suggestive of a renin-secreting tumor given the clinical context (Figs. 1 and 2). A renin-secreting tumor originating in his right kidney was highly suspected. The cardiology team performed a transthoracic echocardiogram that showed a normal left ventricular ejection function of 74% and no pulmonary hypertension. Controlling the patient’s blood pressure was difficult, requiring the administration of numerous antihypertensives: alpha-adrenergic blockade (with phenoxybenzamine) and propanolol. The patient underwent an open right partial nephrectomy by lombotomy. Although the lesion measured only 9 mm, the decision to proceed with open surgery was ultimately made after a comprehensive discussion with the patient. Given his prolonged and severe hypertension, along with significant clinical symptoms, the patient opted for an open surgical approach. It aligned with the patient’s desire for an immediate and definitive resolution of his symptoms. The clamping was pedicular. The warm ischemia time was 18 min. No postsurgical complications were observed in the aftermath of the surgery. The surgical margins were clear. The diagnosis was confirmed by histopathological examination and immune histochemistry tests (Figs. 3 and 4). After surgery, the patient’s plasma renin and aldosterone levels decreased rapidly; Postoperatively, the patient was evaluated at 1 week, 3 months, 6 months, 12 months, and 24 months. At the 1-week follow-up, serum potassium normalized and blood pressure significantly decreased. At 3 months, the patient was asymptomatic and normotensive without medication, with stable renal function. Subsequent visits at 6, 12, and 24 months confirmed sustained clinical stability, no radiological evidence of recurrence, and preserved renal function.

Fig. 1

Renal magnetic resonance imaging demonstrating a 9-mm solid lesion in the right upper pole cortex. A Axial T1-weighted sequence (unenhanced): the cortical lesion is isointense to the renal cortex. B Axial T1-weighted sequence (portal phase, contrast-enhanced): the lesion shows mild enhancement. C Axial T1-weighted subtracted sequence (arterial phase): nodular image without intense enhancement. D Axial T2-weighted sequence: the cortical lesion is T2 isointense compared with the renal cortex

Fig. 2

Axial diffusion-weighted sequence: focal cortical lesion with diffusion hyperintensity

Fig. 3

Histological features demonstrate a juxtaglomerular tumor characterized by a glomoid appearance, exhibiting sheets of polygonal cells with well-defined cell borders and central, round, uniform nuclei. The cells contain a variable amount of clear to eosinophilic cytoplasm

Fig. 4

Tumor cells were diffusely positive for cluster of differentiation 34 (A), negative for AE1/AE3 (B), and focally positive for cluster of differentiation 117 (C)

Discussion

Juxtaglomerular cell tumors (JCT) are tumors originating from the juxtaglomerular apparatus and secreting renin. JCT are rare, with roughly 100 reported cases in literature [2]. Their prevalence is remarkably low, estimated at about 0.03% [2]. The first case was reported in 1967 by Robertson [3]. Juxtaglomerular cell tumors (JCTs) are primarily detected in adolescents and young adults, with a peak incidence in the second and third decades of life. They are twice as common in women as in men. Isolated cases of JCT in children have also been reported [4]. The diagnosis of this tumor is imperative, considering the long-term risk of renal, cardiovascular, and retinal diseases caused by its accompanying severe hypertension. Clinical presentation of this tumor comprises a triad of hypertension, hypokalemia, and an elevated plasma renin activity [5]. They generally do not have metastatic potential, although a case of metastasis has been reported [6]. Changes in blood pressure seen in patients do not correlate with tumor size [7]. In some uncommon instances, the tumor may produce a metabolically inactive renin that does not lead to increased blood pressure levels. A CT scan or MRI is also recommended if there is a clinical suspicion of a renal mass. If a renal mass is detected, it is preferable to choose a surgical resection that preserves the nephrons [7]. Histologically, the tumors are made up of cells that can be polygonal, rounded, or elongated and have a spindle shape. JCT tumors typically stain positive for actin and CD34, while they stain negative for cytokeratins, desmin, S-100 protein, human melanoma black (HMB)45, chromogranin, and synaptophysin. Immunohistochemistry helps differentiate this tumor from renal cell carcinoma and angiomyolipoma, which stain positive for cytokeratins and HMB45, respectively [7]. When treating a metabolically active mass, such as a juxtaglomerular cell tumor, the majority of patients experience a resolution of hypertension and associated symptoms [6, 7]. Recent literature has significantly advanced our understanding of juxtaglomerular cell tumors as a rare renin‐secreting neoplasms that typically manifest with severe hypertension and hypokalemia. Dong et al. [1] performed a comprehensive systematic review of clinical features, laboratory findings, and treatment outcomes in patients with JGCT. Their analysis confirmed that despite the rarity of these tumors, the classical presentation with severe hypertension is consistently observed, and they underscored the diagnostic challenges posed by the often-subtle imaging findings. Complementing these findings, Wang et al. [2] described an atypical case of reninoma, in which the patient exhibited mild hypertension along with normal plasma renin activity but elevated plasma renin concentration. This report expanded the recognized clinical spectrum of JGCTs and highlighted the importance of a thorough biochemical evaluation in suspected cases. Furthermore, Krishnan et al. [7] reported a case in a young male presenting with new-onset congestive heart failure, demonstrating that JGCTs can sometimes manifest with cardiovascular complications beyond hypertension. Collectively, these studies not only reinforce the need for a high index of suspicion when evaluating young hypertensive patients but also emphasize the value of multimodal diagnostic approaches and individualized management strategies. Lobo [8] describes a multi-institutional cohort of JGCTs diagnosed by experienced genitourinary pathologists, evaluating clinical presentation and outcome, morphologic diversity, and, importantly, the molecular features. In total, ten JGCTs were collected from nine institutions, studied by immunohistochemistry, and submitted to whole exome sequencing. His findings highlight the morphologic heterogeneity of JGCT, which can mimic several kidney tumor entities. Three cases showed concerning histologic features; however, the patient course was unremarkable, which suggests that morphologic evaluation alone cannot reliably predict the clinical behavior. Gain-of-function variants in rat sarcoma virus (RAS) GTPases were detected in JGCTs, with no evidence of additional recurrent genomic alterations.

This case contributes to medical literature by demonstrating that even very small reninomas can lead to severe clinical manifestations. Moreover, it highlights the importance of a comprehensive diagnostic work-up and the efficacy of nephron-sparing surgery. The detailed follow-up reinforces the long-term benefits of the chosen management strategy, thereby providing valuable insights for clinicians managing similar cases.

Conclusion

The typical symptoms of a juxtaglomerular cell tumor include hypertension, hyperaldosteronism, and hypokalemia, which occur secondary to elevated plasma renin activity. Partial nephrectomy is the preferred treatment for this type of tumor.