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

Glomus tumor is a rare neoplasm, typically found in superficial soft tissues and extremities, particularly in the subungual region. However, it can also occasionally affect deep soft tissue or viscera, such as the bladder, albeit infrequently. Our patient was a 51-year-old man presenting with recurrent hematuria of unknown etiology, accompanied by a blood clot that resolved spontaneously after 1 day. Abdominal computed tomography revealed multiple calculi in the right kidney, whereas cystoscopy showed mucosal edema on the left side of the bladder. A magnetic resonance image of the bladder identified an ovoid mass on the left side, measuring approximately 3.1 cm × 2.7 cm × 2.1 cm. This mass demonstrated a slightly increased signal intensity on T2-weighted images and an intermediate signal intensity on T1-weighted images. These findings suggested a malignant tumor in the urinary bladder with a nonfunctional right kidney. The patient underwent laparoscopic surgery to remove the right kidney and part of the bladder. Histologically, the tumor primarily consisted of round cells and abundant eosinophilic or pale cytoplasm. Immunohistochemical staining demonstrated diffuse positivity for smooth muscle actin and vimentin, and focal positivity for synaptophysin. The final pathological diagnosis was a bladder glomus tumor. At 15 months after resection, the patient was in good health with no recurrence or metastasis. The clinical manifestations and imaging features of bladder glomus tumors can pose diagnostic challenges for urologists. Therefore, it is imperative to consider this tumor in the differential diagnosis of bladder tumors and to enhance the understanding among urologists and pathologists regarding this entity.