Published online Oct 6, 2021. doi: 10.12998/wjcc.v9.i28.8453
Peer-review started: March 19, 2021
First decision: April 29, 2021
Revised: May 14, 2021
Accepted: July 7, 2021
Article in press: July 7, 2021
Published online: October 6, 2021
Granular cell tumor (GCT) is a neurogenic tumor mainly occurring in the head and neck. GCT in the genitourinary system is extremely rare and only sporadic cases of urinary bladder GCT have been reported. Most urinary bladder GCT cases are benign and only two malignant cases have been reported. Due to its rarity, no consensus criteria for the treatment of urinary bladder GCT are available at present.
A 62-year-old Chinese woman was found to have a urinary bladder tumor without any clinical manifestations on physical examination. Cystoscopy revealed a semispherical shaped lesion measuring approximately 4.0 cm in diameter at the junction of the left wall and roof of the bladder, which was covered with normal bladder mucosa. Computed tomography scan demonstrated a high-density lesion on the left wall of the bladder, measuring approximately 2.9 cm × 2.4 cm with clear boundaries. Contrast-enhanced pelvic magnetic resonance imaging revealed a space-occupying lesion on the left wall of the bladder (non-mucosal origin/ external pressure), which was preliminarily suspected to be a desmoplastic fibroma or leiomyoma. In the context of the above findings, a pre-operative diagnosis of bladder leiomyoma was made. The patient consequently underwent a laparoscopic partial cystectomy. The resected bladder mass looked yellowish and well-demarcated, measuring 4.0 cm × 3.5 cm and infiltrated the muscular layer. The diagnosis of urinary bladder GCT was finally made by postoperative pathology, with positive immunohistochemical S-100 staining and negative pancytokeratin. The patient has been followed for 6 mo so far, with no tumor recurrence detected.
This case highlights the biological feature and differential diagnosis of urinary bladder GCT at the pathological and molecular levels. Transurethral resection of the bladder tumor and partial cystectomy are recommended in most urinary bladder GCT cases, while radical cystectomy is recommended in malignant cases.
Core Tip: ATP6AP1, ATP6AP2, BRD7 and GFRA2 gene mutations can potentially induce the progression of urinary bladder granular cell tumor. Characteristic biomarkers such as S-100, SOX10, CD56, pancytokeratin and HBM45 are essential for the diagnosis and differential diagnosis. Partial cystectomy is the treatment of choice to minimize recurrence and improve disease-free survival in benign cases. A relatively conservative transurethral resection of the bladder tumor can also be an alternative option according to the location of the primary tumor or at the patient's request. For malignant bladder granular cell tumors, radical surgical intervention with pelvic lymph node dissection is necessary.