Multicentric castleman’s disease mimicking IgG4-related disease: A case report

Abstract

A 63-year-old Japanese man was admitted to our hospital for the evaluation of hypergammaglobulinemia, lymphadenopathy, interstitial lung disease and nephritis. His serum level of IgG and IgG4 were 8198 mg/dL and 3360 mg/dL, respectively. Renal biopsy revealed focal interstitial nephritis with IgG4 positive plasma cells, with an IgG4/IgG ratio of >0.6. Inguinal lymph node biopsy showed hyperplasia of the lymphoid follicles with prominent infiltration of mature plasma cells between normal germinal centers. Immunostaining showed that the IgG4-positive plasma cells were prominent, and the IgG4/IgG ratio within the lymph node was >0.8. Although these findings were consistent with IgG4-related disease (IgG4-RD), other laboratory findings such as high serum concentrations of C-reactive protein, interleukin-6, IgA, and IgM, as well as positive staining of the lymph node for IgA and IL-6, suggested multicentric Castleman’s disease (MCD). Following unsuccessful therapy with glucocorticoids, treatment with an anti-interleukin-6 receptor monoclonal antibody (tocilizumab) exerted disease control. Understanding the crucial differences between MCD and IgG4-RD may contribute to understanding the pathogenesis of both diseases.