Primary Renal Carcinoid in patient With Horseshoe Kidney

Document Type

Conference Proceeding

Publication Date

4-1-2022

Publication Title

American Journal of Kidney Diseases

Abstract

Primary renal carcinoid (PRC) tumors are a rare form of neuroendocrine tumor. Less than 1% of carcinoid tumors are located in the genitourinary system1 and fewer than 100 cases have been reported. A significant association between congenital kidney abnormalities and PRC has been described in the literature2. The most common abnormality has been horseshoe kidney. Due to the rarity of these conditions existing concomitantly, only 14 cases have been published to date. We report a case of PRC discovered as an incidental intraoperative finding in a patient with horseshoe kidney. A 57 year-old male with hypertension and hyperlipidemia presented to his primary care provider with chief complaint of nocturia 3-4 times nightly and uncontrolled hypertension. He had no signs or symptoms of carcinoid syndrome. He underwent workup for renovascular hypertension with a CT abdomen/pelvis which revealed a horseshoe kidney. Subsequently, he underwent open partial nephrectomy, in which intraoperative ultrasound identified a mass in the renal isthmus, which was excised. Biopsy revealed a 5.8 cm well-circumscribed tumor with round- to- oval nuclei, immunohistochemical staining positive for cytokeratin and synaptophysin, and rare mitotic figures, confirming a diagnosis of renal carcinoid tumor. No local or distant metastasis was identified in this patient. Horseshoe kidneys have been known to correlate with increased risk for tumors such as Wilms tumor and transitional cell carcinoma (risk 2-fold and (3-4)-fold, respectively). In the most comprehensive study to date, it has been calculated that patients with horseshoe kidney defect have a substantially elevated relative risk (62-fold) for developing PRC when compared to individuals with anatomically normal kidneys2. The reason for this increased risk remains unclear but it has been observed they more often follow a benign course of disease. It has been theorized that the pathophysiology of PRC involves pre-existing hyperplastic neuroendocrine cells as the foci of aberrant epithelium in the kidney2. This case serves to further contribute to the body of literature on the association of congenital renal abnormalities and PRC, with the hopes that we may one day elucidate the whole pathophysiology, clinical course, and optimal management for future patients with this rare tumor.

Volume

79

Issue

4 Supplement 2

First Page

S92

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