Review Curr Urol 2019;13:7–12 Received: July 9, 2018 DOI: 10.1159/000499301 Accepted: July 22, 2018 Published online: September 10, 2019 Juxtaglomerular Cell Tumor: Reviewing a Cryptic Cause of Surgically Correctable Hypertension Rafid Inama Jason Gandhia,b Gunjan Joshic Noel L. Smithd Sardar Ali Khana,e aDepartment of Physiology and Biophysics, Stony Brook Renaissance University School of Medicine, Stony Brook, NY, USA; bMedical Student Research Institute, St. George’s University School of Medicine, Grenada, West Indies; cDepartment of Internal Medicine, Stony Brook Southampton Hospital, Southampton, NY; dFoley Plaza Medical, New York, NY; eDepartment of Urology, Stony Brook Renaissance University School of Medicine, Stony Brook, NY, USA Key Words Introduction Juxtaglomerular cell tumor • Reninoma • Renin • Secondary hypertension • Partial nephrectomy Juxtaglomerular cell tumor (JGCT), or reninoma, is a rare disease resulting from renin-induced hypertension. Dysfunction in juxtaglomerular cells lead to the over- Abstract expression of renin. Although presented with limited Juxtaglomerular cell tumor (JGCT), or reninoma, is a typi- cases, diagnosis of JGCT occurs within young adults and cally benign neoplasm generally affecting adolescents and adolescents with some occurrences within young chil- young adults due to modified smooth muscle cells from the dren [1, 2]. JGCT-induced hypertension is the primary afferent arteriole of the juxtaglomerular apparatus. Patients symptom with other rare occurrences such as myocar- experience symptoms related to hypertension and hypoka- dial infarction. JGCT can coexist with various forms of lemia due to renin-secretion by the tumor. MRI, PET, CT, and cancer, indirectly enhancing those various types of can- renal vein catheterizations can be used to capture JGCTs, cers. In most cases presented within literature, JGCTs are with laparoscopic ultrasonography being most cost-effec- benign tumors in the kidney. Malignant tumors may be tive. Surgical removal is the best option for management; expressed in the kidney or liver, however only a handful electrolyte imbalances are a potential complication which of cases have shown this result. Herein we review the may be assuaged via pre-surgical administration of aliskiren, epidemiology, genetics, histopathology, clinical presen- a renin inhibitor. Considering the vast etiology for hyperten- tation, and management of this rare condition. sion and rarity of JGCT, the diagnosing physician must have a high index of suspicion for JGCT. Early recognition and management can help prevent cardiovascular or pregnancy Anatomy and Physiology of Juxtaglomerular complications and fatalities, vascular invasion and metasta- Apparatus sis, improve quality of life, and limit socioeconomic liabilities. Herein we review the epidemiology, genetics, histopathol- Under normal conditions, the production of the pro- ogy, clinical presentation, and management of this rare con- tease renin occurs within juxtaglomerular cells and the dition. The impact of genetics on prognosis warrant further functions as the rate-limiting step within the renin-an- research. © 2019 The Author(s) Published by S. Karger AG, Basel giotensin system. Renin is converted to its active form © 2019 The Author(s) Sardar Ali Khan Published by S. Karger AG, Basel Department of Urology, Health Sciences Center T9-040 Fax +41 61 306 12 34 Stony Brook University School of Medicine E-Mail [email protected] This article is licensed under the Creative Commons Attribution- 101 Nicolls Road www.karger.com NonCommercial-NoDerivatives 4.0 International License (CC BY- Stony Brook, NY 11794-8093 (USA) NC-ND) (http://www.karger.com/Services/OpenAccessLicense). Usage and distribution for commercial purposes as well as any dis- E-Mail [email protected] tribution of modified material requires written permission. through proteolysis within juxtaglomerular cells and Table 1. Renin-producing tumors included in the differential diag- stored within granules. The number of juxtaglomerular nosis for JGCT cells varies based on age and intensity of stimulation [3]. Renin-producing tumors Renin is rapidly released upon response to a stimulus. Beta-adrenergic receptors are crucial for the rate of renin Adrenocortical carcinoma generation, modulated through cyclic adenosine mono- Adrenal adenomas B-cell leukemia phosphate, the primary catalyst for renin mRNA [4]. The Breast carcinoma angiotensin II pathway contributes as a negative feed- Cystadenocarcinoma back regulator indirectly through mediation of macula Desmoplastic small round cell tumor Endocrine hypertension densa inputs and the baroreceptor [4]. COX-2 and nNOS Hepatoblastoma pathways are other significant regulatory mechanisms of Juxtaglomerular cell tumor renin through fluctuation of PGE2, nitric oxide and PGI2 Wilm’s tumor Uterine leiomyosarcoma [4, 5]. As renin granules function deplete, surface area of the cell membrane increases, leading to oversaturation of renin at a quantal rate [3]. Imbalance of renin secretion hinders neurotransmitter pathways, endocrine and para- crine receptors, and disruptions of cells dependent on cyclic AMP pathway [6]. Other components indirectly Genetics impacted are cAMP response element-binding protein, a substrate essential for renin gene expression, and the re- Based on a dual case study with a 12-year-old patient spective activator p300 [7]. Overproduction of renin es- and 41-year-old patient, genetic analysis revealed a loss calates aldosterone levels, leading to hypertension [2, 8]. in chromosome 9, 11 and X in both tumors. Although no Mechanical disruption has been associated with JGCT pathology has been revealed, the specified chromosomal and connexin proteins within the cellular gap junction. loss may be directly linked to JGCT, as both tumors ex- Substantial depletion of connexin-40 have been asso- pressed JGCT phenotypically [14]. The roles of alleles ciated with JGCT-induced hypertension within a mice p53 and Rb are significant for renin-gene expression. In model [6, 9, 10]. Connexin-45 demonstrates identical ef- an animal study, p53 and Rb alleles were selectively de- fects as connexin-40, to a lesser extent [11]. leted causing elevated levels in glucagon and presence of metastatic tumors [15]. Epidemiology Histopathology There are approximately 100 reported cases of JGCT in the literature. Based on the current cases, diagnosis of There are several other renin-producing tumors that JGCT is consistent between the ages of adolescent and correlate with JGCT, as listed in table 1. Development young adults [2]. It is also twice as common in women as of JGCT as a secondary cause of hypertension can re- men. Suspicion of JGCT is viable within young hyper- main undetected and lead to miscarriage if not treated tensive females [12]. A 60-year-old patient case study re- immediately, as shown previously in a case study [16]. vealed the occurrence of a renal producing tumor shortly Symptoms of desmoplastic small round cell tumor are after a menopausal syndrome diagnosis. Hypertension consistent with that of JGCT. A case study shows a was diagnosed 6 months prior to the procedure. Tumor 20-year-old patient experiencing elevated plasma renin was identified as benign and removed with a unilateral levels, aldosterone, and severe hypertension and hypo- adrenalectomy. Diagnosis of hypertension may indicate kalemia. Desmoplastic small round cell tumor is a ma- the reoccurrence of adrenocortical carcinoma [13]. A lignant tumor and derives from the same mRNA precur- similar case presented in a 12-year-old female patient ex- sor for renin and shares identical metabolic processes as periencing elevated levels of blood renin concentration, JGCT [17]. A similar case is presented in a 4-year-old aldosterone and high blood pressure. Blood potassium male patient diagnosed with Wilms’ tumor. The symp- was slightly decreased from normal ranges, as the patient toms of hypertension and increased renin expression are was experiencing extended salt hunger. CT scan revealed consistent in patients diagnosed with Wilms’ tumor, a 6 cm tumor on her left kidney [14]. possible correlation with undetected JGCT [18, 19]. 8 Curr Urol 2019;13:7–12 Inam/Gandhi/Joshi/Smith/Khan Deletion of RBP-J, a progenitor within bone marrow procedure [27]. Another case study involving a 24-year- which expresses renin, is linked to inducing B-cell leu- old male patient showed a polymorphism of the ACE kemia. Under conditions of JGCT, the expression of RB- gene. The patient underwent thyroidectomy with lymph- P-J is hindered, leading to the overexpression of renin, a adenectomy at the age of 20 according to previous medi- possibility that JGCT and B-cell leukemia may be cor- cal record. Abnormal decrease of urinary catecholamines related [20]. Pro-renin receptors are higher in concentra- and metanephrines were reported with a MRI screening tion when plasma renin levels are elevated, a symptom of of a lesion on the right kidney confirming diagnosis of JGCT. Pro-renin receptors have been associated in cell JGCT and pheochromocytoma. proliferation within breast cancer cells [21]. Pro-renin receptors were overexpressed in 4 types of breast cancers Laboratory Studies causing small RNA interference of healthy cells [21]. Severe hypokalemia and hyperaldosteronism have Cystadenocarcinoma (ovarian cancer) identified in a been reported before diagnosis of JGCT. Increased levels 46-year-old patient, included hypertension, hypokalemia of kaliuresis, plasma renin, pro-renin, and aldosterone