[Localized amyloidosis of the urinary bladder: a case report].

Amyloidosis is characterized by extracellular deposition of abnormal insoluble fibrils, which cause structural and functional disorders. Amyloidosis is classified into systemic and localized amyloidosis. Localized amyloidosis in individual organs is uncommon. We report a rare case of localized form of primary amyloidosis of the urinary bladder. A 76-year-old male visited our hospital with a complaint of macroscopic hematuria. Cystoscopy showed submucosal hematoma in the anterior wall and broad-based mass occupying the trigone without normal mucosa covered by calcification. Transurethral biopsy and resection were performed. Histopathological diagnosis was AL type amyloidosis occupying submucosal extracellular space. We gave the patient occlusive dressing with dimethyl sulfoxide. In 12 months, cystoscopy and magnetic resonance imaging revealed improvement of the mass-like lesion in the bladder wall.