Dear Editor,

Renal involvement is a complication of plasma cell dyscrasias. Electrochemical properties of abnormal light chains are responsible for histological renal pictures. Bortezomib is the first proteasome inhibitor approved for treatment of multiple myeloma and amyloidosis. It prevents the activation of NF-kB that controls the genes encoding IL-6, TNF-alpha and other cytokines and growth factors. Our experience: a 29-year-old woman, suffering from ulcerative colitis successfully treated with sulfasalazine, without renal disease history, was admitted to hospital for acute kidney injury (creatinine 10mg/dL) and anaemia without signs of thrombotic microangiopathy. Serum protein electrophoresis showed a beta-2-monoclonal peak; the serum immunofixation was positive for λ light chains; k- and λ-free light chains (FLC) levels were 37mg/L and 1750mg/L respectively with k/λ ratio=0.02. Microbiological, coagulation and other immunological investigations were unremarkable. The patient started haemodialysis treatment. Renal biopsy revealed a cast-nephropathy picture, negative Congo-red staining, without glomerular deposits; the immunofluorescence showed k light chains but not λ light chains in tubular basement membranes. Abdominal fat biopsy was positive for AL amyloid. Bone marrow biopsy showed 10% of plasma cells infiltration without morphological or cytometric clonality markers; total body CT scan was negative for bone lesions. Because of plasma cell dyscrasia and severe renal involvement, even in absence of a diagnostic definition, was performed a combination treatment of direct removal of FLCs and chemotherapy. Following Hutchison’s studies,1,2 we performed extended haemodialysis (HD) treatment with high cut-off (HCO) dialyzers (Theralite®, Gambro) and bortezomib 1.3mg/m2 + dexamethasone 20mg/day (days 1-4-8-11) therapy with improvement of renal function (creatinine 1,6mg/dL) and normalization of FLC chains levels (k- and λ-FLC 5mg/dL and 6mg/dL respectively with k/λ ratio=0.85) after the first chemotherapy cycle and 7 HCO-HD. Later, we performed 3 additional cycles with bortezomib + dexamethasone at weekly administration (days 1-8-15-22 for a 35 days cycle) and a peripheral blood stem cells harvest for autologous transplantation program.

Conflict of interest

The authors declare that they have no conflicts of interest related to the contents of this article.