Renal histological lesions and clinical syndromes in multiple myeloma. Renal Immunopathology Group.

This retrospective multicenter study, based on 42 patients affected by renal damage due to multiple myeloma, analyzes the renal biopsy results, the clinical data at the time of biopsy and the subsequent renal outcome in order to clarify the correlations existing between clinical and histological changes. Plasmocytoma components were Bence Jones alone in 55% of the patients and light-chain excretion was present in over 90%. Rapidly progressive renal failure was the most frequent clinical presentation (27 cases). The histological lesions directly attributable to multiple myeloma were subdivided into 3 basic categories: related to light-chains, direct tumor involvement of renal parenchyma and attributable to systemic effects of neoplastic disease. Light-chains seemed to cause renal lesions in 59.4% of the cases. Myeloma cast nephropathy was the prominent bioptic diagnosis established (20 cases). Among the clinical, laboratory and histological parameters studied, only the degree of tubular-interstitial damage was significantly correlated to the renal outcome in the 32 patients who had an adequately documented follow-up period.