Differential Diagnosis (2): Castleman Disease

Abstract

Multicentric Castleman disease is a rare benign lymphoproliferative disorder associated with excessive interleukin-6 production. It typically presents with systemic features and can involve multiple organs, including the lymph nodes, lungs, skin, and kidneys. Because some cases of multicentric Castleman disease show high serum IgG4 level and numerous IgG4-positive plasma cell (IgG4+PCs) infiltrates within lymph nodes and other tissues, this disease of sometimes difficult to differentiate it from IgG4-related disease (IgG4-RD) on the basis of histological findings alone.

Relatively little attention has been given to the kidneys with regard to differentiating between these two diseases. We therefore report here our own experience with three cases of multicentric Castleman disease that presented with tubulointerstitial nephritis mimicking IgG4-related kidney disease. The relative paucity of fibrosis and the absence of immune complex deposition in the Castleman cases helped distinguish this diagnosis from IgG4-related kidney disease. Moreover, clinical findings such as high serum C-reactive protein levels and resistance to glucocorticoid treatment were crucial features of Castleman disease, contrasting sharply with IgG4-RD. Elevated serum concentrations of IgG4 and the finding of IgG4+PC infiltrates in systemic organs, including the kidneys, were common to both conditions.