A Report of Three Cases

TLDR

Autopsy studies of 23 long‑surviving cystic fibrosis patients in Boston found no evidence of amyloidosis. The study reports the pathological features of three cystic fibrosis patients with amyloidosis. Immunohistochemistry and potassium‑permanganate pretreatment of tissue sections confirmed the amyloid as secondary (AA) type. Renal biopsy and autopsy revealed AA amyloid deposits in kidneys, spleen, and liver of three cystic fibrosis patients, with markedly elevated serum amyloid A and variable organ involvement, indicating that secondary amyloidosis is an emerging but rare complication in long‑term survivors.

Abstract

The authors report the pathologic features of three cases of amyloidosis associated with cystic fibrosis. Renal biopsy led to the diagnosis (case 1) or suspicion (case 2) of amyloidosis in patients who were 23 and 21 years old, respectively. The third patient died at age 22 years, and amyloidosis was not discovered until autopsy. Immunohistochemical staining and potassium-permanganate pretreatment of histologic sections in all three cases provided evidence that the amyloid seen in these patients is of the secondary (AA) type. Congo red staining in each case and electron microscopy in case 1 confirmed the initial diagnosis of amyloidosis. A markedly elevated serum amyloid A protein (160 μg/mL; normal less than 1 μg/mL) in case 1 indicated the presence of large quantities of the precursor protein from which the AA fibrils of secondary amyloid are derived. The kidneys, spleen, and liver contained amyloid deposits in autopsy material from all three cases. Involvement of other organs by amyloid was variable. Review of autopsy material in Boston from 23 additional cystic fibrosis patients with long-term survival did not reveal any evidence of amyloidosis. It appears that secondary amyloidosis is emerging as a significant, although rare, complication of cystic fibrosis as greater numbers of these patients survive into adult-hood.