Bladder leiomyosarcoma, a formidable and elusive neoplasm of mesenchymal origin, represents a diagnostic and therapeutic challenge due to its insidious progression and intrinsic resistance to conventional chemotherapeutic regimens. Arising from the detrusor muscle, this rare entity often masquerades as other urothelial malignancies, necessitating a meticulous, multidisciplinary approach. We present a case of high-grade bladder leiomyosarcoma, initially manifesting with gross hematuria and lower urinary tract symptoms, to illuminate the complexities of diagnosis, surgical intervention, and oncological surveillance.

A 52-year-old male, with a history of right inguinal hernia, reported a month-long history of gross hematuria, dysuria, urgency, and nocturia. Urinalysis revealed profound hematuria and pyuria, though successive urine cultures yielded no bacterial growth. Cystoscopic evaluation unveiled a substantial, polypoid mass encroaching upon the left bladder neck, raising the specter of malignancy. The patient underwent transurethral resection of the bladder tumor (TURBT), during which a 5 cm mass spanning the left anterior and lateral bladder walls was resected. Histopathological examination delineated a proliferation of spindle cells with cigar-shaped nuclei, moderate nuclear atypia, increased mitotic activity (up to 3/HPF), and foci of tumor necrosis. Immunohistochemistry substantiated the diagnosis, demonstrating robust positivity for SMA, actin, caldesmon, and desmin, with CD117 negativity. Subsequent imaging—including computed tomography and a whole-body bone scan—excluded residual tumor burden or distant metastatic dissemination.

Postoperatively, the patient exhibited transient febrile episodes, peaking at 38°C, which resolved with supportive management. Hemodynamically stable, he was discharged in a satisfactory condition. Follow-up cross-sectional imaging corroborated the absence of locoregional recurrence or systemic metastases. Given the completeness of resection and the absence of residual disease, adjuvant therapy was deferred in favor of vigilant surveillance.

Bladder leiomyosarcoma epitomizes a rare yet aggressive malignancy necessitating a high index of suspicion, thorough histopathological interrogation, and precision-driven surgical excision. This case underscores the indispensable role of multimodal imaging, meticulous pathological assessment, and long-term oncological vigilance in optimizing patient outcomes. With its predilection for recurrence, even in ostensibly resected cases, persistent follow-up remains paramount to preempt disease resurgence.