[IgG kappa myeloma with Fanconi's syndrome and crystalline inclusions. Immunohistochemical and ultrastructural study]

Abstract

An IgG kappa light-chain myeloma, remarkable for the presence of inclusions in plasmocytes and proximal renal tubular cells, was discovered during investigations for renal failure associated with partial Fanconi's syndrome. An immunohistochemical study showed that the crystalline inclusions were positive for IgG and kappa light-chain in plasmocytes and exclusively for kappa light-chain in the renal tubular cells. An ultrastructural study showed that the inclusions were localized in lysosomes and had a 55 A periodicity. This case is similar to the forty odd myelomas or light-chain diseases reported in the literature and revealed by Fanconi's syndrome. Their prognosis is good, with a slow progression towards late renal failure. In our patient the preference of lesions for proximal tubular cells, the site of protein catabolism, was particular since in myelomas they are usually located in the distal tubular cells.