Renal complications in multiple myeloma.

Renal complications were studied in 81 autopsied patients suffering from multiple myeloma (47 male, 34 female, mean age 66.3 years). Kidney samples were examined for the presence of Bence Jones cast nephropathy, light chain deposition disease, amyloidosis, nephrocalcinosis, chronic urate nephropathy, acute renal failure, renal vein thrombosis, acute and chronic pyelonephritis, and tumorous infiltration of the kidney tissue. Lesions were graded under the light microscope as minimal, mild, moderate or severe. This grading and the corresponding serum creatinine levels were used to distinguish four groups: 1. morphologically and functionally intact kidney (40 cases); 2. kidney involvement with good renal function (10 cases); 3. kidney involvement with moderate chronic renal insufficiency (16 cases); 4. kidney involvement with chronic uraemia (15 cases). In patients with an impaired renal function (groups 3 and 4), Bence Jones cast nephropathy occurred most frequently (27 cases, 33%); all other complications were seen much less frequently. Among the 81 patients, two cases of kappa light chain deposition disease and three cases of amyloidosis were found. Although the semiquantitative morphology and serum creatinine levels displayed a good correlation, there were cases with marked histological changes but only a moderate impairment in renal function, suggesting that the drawing of functional conclusions from morphological changes of the kidney requires caution.