Membranoproliferative Glomerulonephritis and Mixed Cryoglobulinemia as a Form of Presentation of Visceral Leishmaniasis.

BACKGROUND Visceral leishmaniasis (VL) is an endemic systemic disease in the Mediterranean countries, including Spain. This vector-borne infection can present with several clinical presentations, from asymptomatic to severe forms. Renal impairment is frequently described in VL but is usually mild and related to interstitial nephritis, being that glomerular involvement is rarely found. CASE REPORT We describe a case of a 69-year-old Spanish male presenting with subacute renal failure due to membranoproliferative glomerulonephritis and mixed cryoglobulinemia accompanied by other autoimmune features (hypocomplementemia, antinuclear and antiDNA antibodies). No hepatosplenomegaly was found with abdominal ultrasound. Hepatotropic viruses and human immunodeficiency virus serological markers were negatives. We initially suspect the presence of an autoimmune disease and the patient was treated with steroids without improvement. After an extensive study including renal and bone marrow biopsy, a correct diagnosis of visceral leishmaniasis was made, and treatment with liposomal amphotericin B was initiated, achieving renal function recovery and normalization of immunological manifestations. CONCLUSIONS Renal involvement can be an important feature of VL and it might be associated with increased morbidity and mortality. The association between mixed cryoglobulinemia and renal involvement in VL have rarely been described. VL is frequently associated with diverse autoimmune manifestations and it can be initially misdiagnosed, which could lead to fatal consequences. The role of the immune system in the formation of cryoglobulins are discussed. In our case, an autoimmune disease was initially suspected, and starting treatment with steroids pulses was initiated. However, the presence of mixed cryoglobulinemia in this patient who was hepatitis C serological marker negative and who had poor renal function recovery after immunosuppressive treatment made us suspect other pathologies. The presence of cryoglobulinemia with renal disease in endemic areas of Leishmania should make us exclude this infection before starting immunosuppressive treatment.

IgG4-related disease and idiopathic membranous nephropathy: "The clothes do not make the man"
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This case report describes a patient with a previous history of autoimmune pancreatitis secondary to IgG4-related disease, who developed an overt nephrotic syndrome due to membranous nephropathy, surprisingly idiopathic. In all the previously described cases with both concurrent diseases, membranous nephropathy was considered to be secondary to the IgG4-related disease based on the absence of anti-PLA2R1 autoantibodies, and nephrotic syndrome usually remitted after treatment with steroids alone. However, in our patient positivity of serum anti-PLA2R1 autoantibodies together with a normal serum IgG4 level, and the absence of the other most commonly associated diseases were compatible with an idiopathic membranous nephropathy. Combination treatment with steroids and cyclophosphamide was successful. We hypothesize about causality or coincidental diseases and the importance of a correct classification.
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