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CHARACTERISTICS OF THE RENAL DAMAGE: Type I cryoglobulinemia, composed of a single monoclonal immunoglobulin, may be responsible for a glomerulopathy with clinical presentation and histological characteristics close to those of mixed cryoglobulinemia.Type I cryoglobulins complicate a malignant haematological disease, chronic lymphoid leukaemia or non-Hodgkin's malignant lymphoma in 60% of cases.Treatment with corticosteroids and immunosuppressors or antimitotics often leads to the parallel stabilisation or remission of the renal manifestations and the haematological disease

THE CONTEXT: Type II cryoglobulinemia, composed of a monoclonal IgM rheumatoid factor directed against polyclonal IgG, is associated in most cases with chronic hepatitis C viral infection. THE CHARACTERISTICS OF RENAL DAMAGE: Frequent, the renal damage usually occurs after the onset of various systemic manifestations and is expressed by moderate renal failure, microscopic haematuria, proteinuria lower than 3 g/d and hypertension difficult to control. More severe aspects are possible such as acute nephrotic or nephritic syndromes, or even multi-organ failure with anuria. A renal biopsy confirms the diagnosis by revealing a membranoproliferative glomerulonephritis, characterized by the intensity of the monocyte infiltration and glomerular deposits, often arranged in curved microtubules under electronic microscopy and often associated with vasculitis lesions. Progression towards terminal renal failure is rare.Treatment, unclearly defined, relies on anti-virals (interferon a and ribavirin), which are partially effective when the viral replication is inhibited, associated with corticosteroids and immunosuppressors or even plasma exchange in the severe forms. The management and treatment of the cardiovascular complications condition the vital prognosis.

Side-effects, including autoimmune disorders, are frequent with D-penicillamine therapy. Proteinuria is observed in 10% of the patients, often secondary to extramembranous glomerulopathy. Necrotizing extracapillary glomerulonephritis is however exceptional.Two patients with systemic sclerodermia were treated with D-penicillamine for 7 and 14 years. Both developed necrotizing extracapillary glomerulonephritis with anti-myeloperoxidase antibodies (anti-MPO), associated with hemorrhagic alveolitis in one case. Partial regression of the renal failure was obtained after withdrawal of D-penicillamine and combination treatment with prednisone and cyclophosphamide.Extracapillary glomerulonephritis or a lung-kidney syndrome are frequently associated with anti-MPO antineutrophil cytoplasm antibodies (ANCA). In systemic sclerodermia, the presence of anti-MPO appears to define a group of patients at risk of pauci-immune extracapillary glomerulonephritis or a lung-kidney syndrome. In addition, the presence of ANCA in patients with renal failure would suggest extracapillary glomerulonephritis rather than sclerodermic microangiopathy. Development of extracapillary glomerulonephritis with anti-MPO in patients who are taking D-penicillamine suggests that inductor mechanisms other than D-penicillamine are involved in the pathogenesis of these glomerulopathies.