Cancer-Associated AA Amyloidosis Presenting as Crescentic Glomerulonephritis

Abstract

Glomerular crescents are not generally regarded as a distinct pathology in renal amyloidosis. Yet up to 13.3% of cases of renal amyloidosis that have been reported show at least focal crescent formation.1 Thus, crescents may be a frequently overlooked finding in cases of renal amyloidosis. Amyloidosis is a relatively uncommon disease (the incidence is about 5−10 cases per million patient-years), resulting from abnormal deposition of autologous protein fibrils that aggregate to form a cross-β sheet quaternary structures. The kidney is 1 of the most affected organs. The etiology of renal amyloidosis is heterogeneous. The most common types of amyloid to involve the kidney are light chain amyloidosis (AL-amyloidosis), serum amyloid A (AA amyloidosis), and leukocyte cell–derived chemotaxin 2 (ALECT2 amyloidosis). Serum amyloid A amyloidosis makes up approximately 40% of renal amyloidosis cases. The primary etiologies for AA amyloidosis include rheumatoid arthritis and familial Mediterranean fever. A rare etiology for AA amyloidosis is solid tumors (etiology in <10% of AA amyloidosis cases).2, 3 Here we present 2 cases of renal AA amyloidosis in patients with underlying solid organ malignancies (renal cell carcinoma and cervical squamous cell carcinoma), both of which manifested as a crescentic glomerulonephritis.