Primary localized amyloidosis of the urinary tract frequently mimics neoplasia: a clinicopathologic analysis of 11 cases.

Localized urinary tract amyloidosis (UTA) is a rare disease that mimics neoplasia clinically, cystoscopically, and radiologically. We report eleven cases of isolated UTA from the urinary bladder (n=7) and upper urinary tract including the ureter (n=2) and renal pelvis (n=2). All cases clinically presented as mass lesions prior to histologic examination and clinically suggested a neoplastic process. The amyloid composition in most cases was mixed Kappa and Lambda light chains. All cases were cured after surgical excision except one case which was diagnosed as plasmacytosis/plasmacytoma six months later. Localized amyloidosis of the urinary tract usually has a benign clinical course and simple resection is recommended after systemic disease is ruled out.