We describe a 59-year-old man with
nephrotic syndrome that was diagnosed as suspected
minimal change nephrotic syndrome by the routine examination of renal tissues at first biopsy, because renal histology showed segmental mild mesangial expansion with argyrophilic staining and partial foot process fusion without any deposition.
Prednisolone therapy induced complete remission of
nephrotic syndrome. Relapse occurred after 4 years of complete remission, and the second renal biopsy revealed
amyloid light-chain (
AL)-amyloidosis. Re-examination of the first biopsy tissues by
Congo red staining confirmed a small amount of
amyloid deposition in the mesangial areas although the mesangial areas showed argyrophilic staining, which is atypical for
amyloid deposition. This case raises a caution that even when renal histology is not suggestive of
amyloidosis and
prednisolone therapy is very effective, when a renal histology diagnosis is not confirmed, the clinician should suspect
amyloidosis and should, at least, undertake
Congo red staining to definitively rule out
amyloidosis.