Extra-gastrointestinal Stromal Tumor of the Urinary Bladder: A Report of a Rare Case and Literature Review

Extra-gastrointestinal stromal tumors (eGISTs) are rare tumors that occur outside the gastrointestinal tract but share similar histological and molecular characteristics as GISTs. This report highlights an exceptionally rare case of eGISTs in the urinary bladder of a 40-year-old man who presented with painless gross total hematuria. Computed tomography (CT) revealed a solitary bladder mass, approximately 3 × 3 cm over the anterior wall, with extravesical extension into the urachal remnants. He was diagnosed with eGIST of the urinary bladder based on histopathology and immunohistochemistry after cystoscopy and transurethral resection. The patient underwent open partial cystectomy and excision of the urachus, with an uneventful recovery and no recurrence at 28 months follow-up. This case report underscores the importance of recognizing and appropriately managing bladder eGISTs.