Benign Glomus Tumor of the Urinary Bladder: A Case Report and Literature Review.

Introduction: Glomus tumors (GT) are sporadic mesenchymal neoplasms found in adults, comprising less than 2% of soft tissue tumors. GT originates from glomocytes, which are modified vascular smooth muscle cells located in the walls of specialized structures of the glomus body—a neuromyoarterial plexus in the dermis of the skin that typically plays a role in thermoregulation. Most GTs are benign, though some cases exhibiting atypical or malignant behavior have been documented. GT usually occurs in the skin and superficial soft tissues, primarily in the extremities, especially beneath the nail bed, and rarely affects internal organs; however, those organs lack glomus bodies. The occurrence of GT in the urinary bladder, which does not contain glomus bodies, is an infrequent occurrence and has been reported sporadically. The gene implicated in the pathogenesis of bladder GT is the glomulin gene (GLMN), situated on chromosome arm 1p21-22. Multiple subungual granular tumors (GTs) have been reported in neurofibromatosis type 1, originating from a mutation in the NF1 gene. The first case of benign GT of the urinary bladder was described by Tripodi SA et al. in 2013, while malignant GT of the urinary bladder was described by Shim HS et al. in 2005. Depending on the relative prominence of glomus cells, vascular structures, and smooth muscle, the GTs are subcategorized: Solid histotype, Glomangioma, and Glomangiomyoma. In this study, we report a case of benign GT of the urinary bladder in a 63-year-old man presenting with recurrent hematuria of unknown etiology. The cystoscopy showed a polypoid lesion at the anterior wall of the urinary bladder. The transurethral resection was performed, and the lesion was easily removed. In the microscopic examination of the biopsy, the final pathological diagnosis was a benign glomus tumor of the urinary bladder – a solid histotype. After resection of GT, the patient was followed according to standard follow-up protocol for patients with bladder tumors. One year after resection, the patient was in good health, with no recurrence or metastasis, demonstrating the successful treatment and follow-up of this rare case. Conclusions: GTs arising in the bladder are extremely rare. It is challenging to diagnose bladder GTs based on their clinical features. The gold standard method for diagnosing GT is histopathological examination and immunohistochemical analysis. Transurethral resection is the most common treatment used for benign or atypical bladder GT. However, it should also be considered in the differential diagnosis for Bladder neoplasms.