膀胱平滑肌瘤 – 案例報告

徐震翰¹、顧明軒^1,2,3、黃逸修^1,2,3

¹台北榮民總醫院 泌尿部；²陽明大學醫學院泌尿學科；³書田泌尿學研究中心

Bladder Leiomyoma : A Case Report

Chen-Han Hsu¹, Ming-Hsuan Ku^1,2,3, Eric Yi-Hsiu Huang^1,2,3

¹Department of Urology, Taipei Veterans General Hospital, Taipei, Taiwan

²Department of Urology, School of Medicine, National Yang-Ming University, Taipei, Taiwan

³Shu-Tien Urological Institute, National Yang-Ming University, Taipei, Taiwan

Introduction:

Bladder leiomyoma is a rare benign mesenchymal tumor arising from smooth muscle cells of the urinary bladder and accounts for less than 0.5% of all bladder tumors. Because clinical and radiologic findings are often nonspecific, these lesions may mimic malignant bladder neoplasms and require histopathological confirmation for definitive diagnosis.

Case Report:

A 73-year-old woman with a history of hypertension was admitted because of fever and low back pain. During the evaluation for fever of unknown origin, abdominal computed tomography incidentally revealed a 1.8 × 2.4 cm soft tissue lesion arising from the urinary bladder. The patient denied gross hematuria or lower urinary tract symptoms. Urine cytology was negative for malignant cells. Cystoscopic examination demonstrated a submucosal bladder lesion, and transurethral resection of the bladder tumor (TUR-BT) was subsequently performed. A submucosal bladder mass was identified on cystoscopy. A clear dissection plane was identified during TURBT, allowing the tumor to be separated from the surrounding muscular tissue using an enucleation-based approach. Histopathological examination showed proliferation of spindle-shaped smooth muscle cells arranged in intersecting fascicles without significant nuclear atypia. Immunohistochemical staining demonstrated positivity for desmin and h-caldesmon, supporting the diagnosis of bladder leiomyoma. The postoperative course was uneventful, and the patient remained asymptomatic, with no radiographic evidence of recurrence on CT and ultrasound at 6 months postoperatively.

Discussion

Bladder leiomyoma most commonly occurs in women between 40 and 60 years of age and is usually discovered because of lower urinary tract symptoms or hematuria. In contrast, our patient was older than the typical age group, and the lesion was discovered incidentally during investigation for an unrelated febrile illness. Cystoscopic findings of our case were consistent with existing literature, identifying a submucosal bladder mass characterized by smooth and regular overlying mucosa. Small submucosal bladder masses may be difficult to distinguish radiologically from urothelial carcinoma or other spindle cell tumors. Therefore, pathologic examination remains essential. The absence of cytologic atypia and the presence of smooth muscle markers, including desmin and h-caldesmon, favored a diagnosis of leiomyoma over leiomyosarcoma or other mesenchymal tumors.

Conclusions:

Although uncommon, bladder leiomyoma should be considered in the differential diagnosis of an incidental submucosal bladder mass. Histopathological and immunohistochemical evaluation is necessary to establish the diagnosis. Complete transurethral excision is both diagnostic and therapeutic, with an excellent prognosis and very low risk of recurrence. Enucleation could be achieved as distinct dissection plane could exist between the lesion and the surrounding muscular tissue.