Amyloid A-type renal amyloidosis in a patient with sarcoidosis: report of a case and review of the literature.

A 53-year-old man developed chronic renal failure during a protracted course of sarcoidosis. A renal biopsy showed Congo red-positive homogenous deposits in the subendothelial space of glomerular capillary walls and arterial walls. On electron microscopy, amyloid fibrils were observed in the deposits. Immunohistochemistry showed positive staining for amyloid A (AA) protein. Treatment with prednisolone resulted in poor response, followed by progressive deterioration of renal function requiring hemodialysis. To our knowledge, there are 5 cases with histologically proven renal amyloidosis accompanied by sarcoidosis. Prognosis in these patients is extremely poor. AA-type amyloidosis should be considered as a rare renal complication in the setting of long-standing sarcoidosis.