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IgA nephropathy in a patient with IgG lambda light-chain plasmacytoma: a rare coincidence.

Renal involvement in multiple myeloma (MM), which accounts for about 10% of all haematological malignancies, is not uncommon. Immunoglobulin A (IgA) nephropathy and IgA lambda myeloma with mesangial proliferative glomerulonephritis (GN) have been reported [1]. An interaction between mesangial cells and IgA as well as IgG immune complexes provides a possible mechanism for glomerular injury in IgA nephropathy [2]. IgA myelomatosis with nephritis and Henoch-Schoenlein purpura may coexist [3], and some have suggested a causal relationship between IgA nephropathy and IgA myeloma [4]. Unlike findings in patients with lupus-GN and other types of proliferative and membranous GN, patients with IgA nephropathy have positive staining for kappa(k) and lambda-( ) immunoglobulin in their kidney biopsies [5], with more intense staining of the -light-chain than for the k-light-chain. Activation of the transcription factor nuclear factor kB (NF-kB) has been shown to be involved in the development of human GN, and the degree of glomerular expression of NF-kB correlated with the progression of glomerular injury in IgA nephropathy [6]. Inhibitors of NFkB may provide potential agents for treatment of immune GN [7], since inhibition of NFkB prevented inflammation in an experimental model of renal failure [8]. We report a patient with a plasmacytoma of the sacrum given local irradiation, various cytostatics and with thalidomide that showed acceptable responses during several years of treatment. Six years later the disease flared-up. Pneumonia and renal failure due to de novo IgA nephropathy developed and regular haemodialysis was started. Treatment with the NFkB inhibitor bortezomib resulted in temporary regression of the myeloma, recovery of kidney function and disappearance of IgA deposits in a repeat kidney biopsy.