[Case of Henoch-Schönlein purpura nephritis complicated with essential mixed cryoglobulinemia].

We report a case of purpura nephritis complicated with essential mixed cryoglobulinemia. The patient was referred to our hospital because of a petechial rash on the lower extremities, microscopic hematuria, and progressive deterioration of renal function. The presumptive diagnosis of Henoch-Schönlein purpura (HSP) was made, and the patient was treated with prednisolone at the dose of 40 mg/day. However, there was a persistent purpuric skin rash. On the other hand, immunoelectrophoresis of the serum revealed the presence of IgA-lambda and polyclonal IgG in the cryoprecipitate. Granular staining for polyclonal rather than monoclonal IgA and C3 segmentally along the capillary walls demonstrated by immunofluorescence analysis of renal biopsy led to the diagnosis of purpura nephritis as the major mechanism of renal damage. After three sessions of cryofiltration, the patient's serum cryoglobulins decreased and the active rash finally settled, along with improvement of renal function. These observations suggest that the presence of cryoglobulinemia modulated the clinical course of HSP in our case. Therefore, the possibility of the latent presence of cryoglobulinemia in cases with HSP having an active rash refractory to steroid treatment should not be overlooked.