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Introduction. Kidney manifestations are frequent in multiple myeloma (MM) patients. It’s mechanisms and clinic manifestations are diverse. We share the experience of an infrequent MM variety, with outstanding kidney biopsy findings.
A 66 year-old stonemason presented with bilateral leg edema for more than 1 year. Laboratory showed Previous serum creatinine 0.9 mg/dL. Serum creatinine at admission was 3.5 mg/dL, Hb 10.3 g/dL, serum calcium 11.4 mg/dL, urianalysis revealed proteinuria and glycosuria. Serum albumin 2.4 g/dL.
Renal ultrasound findings were not relevant. 24 hour protein reported 10.2 gram, albuminuria 4979 mg. Nephrotic syndrome with renal failure was diagnosed. TTE suggested infiltrative cardiomyopathy. Bone marrow aspiration reported 40% of plasma cells. Renal biopsy reported Nodular glomerulopathy, Congo Red negative, with Kappa positive and Lambda negative staining, suggesting light chain disease.
An M-protein in beta region was shown in urine protein electrophoresis. Serum free light chain were positive with a κ/λ 0.17. Serum protein immunofixation detected monoclonal κ ligh chains. Bence-Jones protein was absent. A diagnosis of κ light chain multiple myeloma was made and patient was transferred to a specialized hemato-oncological facility for treatment initiation. There he received the first dose of dexamethasone and bortezomib. One month later after losing follow-up the patient died.
Although cast nephropathy is described as the most common presentation of kidney damage in MM patients, alterations in any nephron compartment may be present, with varied glomerular syndromes In this case we report light chain deposit disease with a nodular lesions in kidney biopsy, associated with κ light chain multiple myeloma. The presentation was nephrotic syndrome with kidney failure, anemia and hypercalcemia. Multiple myeloma criteria were met (bone marrow plasmocytes infiltration >10%, hypercalcemia, anemia, kidney damage).
This case is unusual because of the long standing nephrotic syndrome, M-protein in beta region, and the biopsy findings that are not common in previously reported cases. left us useful lessons for the approach to patients with MM and confirms the role of renal biopsy in these cases. Nephrologists must have a low threshold of suspicion to look for paraproteinemia in these patients.