Amyloidosis of the bladder and association with urothelial carcinoma: report of 29 cases.

The association of amyloidosis with certain neoplastic processes is well known. Amyloid uncommonly occurs in relationship with other epithelial neoplasms including urothelial carcinoma. Herein, we report 29 cases of amyloidosis in the bladder, 14 of which were found in relationship to urothelial carcinoma. With institutional review board approval. We searched pathology archives for cases of amyloidosis in the bladder. Clinical, laboratory, and surgical pathology records were reviewed, and data were recorded for all cases. Diagnosis of amyloid was made by Congo red stain showing apple-green birefringence on polarization microscopy and special studies in some cases. Twenty-nine cases of amyloid were identified in bladder specimens. Presentation as a mass lesion was the most common (n = 18). Immunohistochemical subtyping done in 17 cases showed transthyretin-type (n = 10), AL (n = 3), AA (n = 1), amyloid P (n = 1), and undetermined (n = 2) types of amyloid. Eighteen (62%) cases were classified as localized primary amyloidosis and 11 (38%) as secondary manifestation of systemic amyloidosis. In 14 (48%) cases, there was an associated urothelial carcinoma: 5 urothelial carcinoma in situ, 4 low-grade noninvasive papillary urothelial carcinoma, 2 high-grade noninvasive papillary urothelial carcinoma, and 3 high-grade invasive urothelial carcinoma. Associated urothelial carcinoma was present in 4 of 7 patients with systemic amyloidosis and 10 of 18 patients with localized amyloidosis, with the difference not being statistically significant (P = .45). Amyloidosis of the bladder is rare and presents as a mucosal mass or hematuria that may mimic urothelial carcinoma. In this study, we found urothelial carcinoma occurring in 48% of the cases in association with amyloidosis, a finding not previously reported. The relationship of amyloid in the bladder and urothelial carcinoma, although likely not causal, appears to be a unique finding not frequently seen with other solid tumors.