Increased interleukin-6 (IL-6) production in a young child with clinical and pathologic features of multicentric Castleman's disease

A 21-month-old boy presented with a papular rash, lymphadenopathy, and splenomegaly. He developed symmetric polyarthritis, fever, and progressive glomerulonephritis. Serologies for viral agents including HIV were negative. Antinuclear antibody was transiently positive, but no anti-DNA antibodies were present. CH50 and serum C3 values were low. Biopsies of skin, kidney, bone marrow, and lymph node were obtained. There was a perivascular and periadnexal lymphocytic infiltrate in the skin, with a normal epidermis. Renal biopsy showed proliferative mesangial glomerulonephritis. Bone marrow showed an increased number of plasma cells. Lymph node showed histologic changes described in multicentric Castleman's disease including marked follicular hyperplasia, vascular proliferation, and interfollicular expansion with numerous plasma cells. IL-6 mRNA was demonstrated in cells in the marginal zone and interfollicular regions of the node by in situ hybridization. Likewise, the serum IL-6 level was elevated during a clinical exacerbation of the patient's nephritis. These data suggest an underlying lymphoproliferative disorder, such as Castleman's disease, with overproduction of IL-6 resulting in systemic features of the disease, including glomerulonephritis.