Idiopathic multicentric Castleman disease presenting progressive reticular honeycomb infiltration of lung and immunoglobulin G and immunoglobulin G4 dominant hypergammaglobulinemia: a case report.

Multicentric Castleman disease (MCD) is an uncommon systemic lymphoproliferative disorder that may cause multiple organ damage. Castleman disease-associated diffuse parenchymal lung disease (DPLD) has not been well studied. A 32-year-old man was referred to our hospital for progressive generalized weakness, light-headedness, and dyspnea on exertion for more than one year. Laboratory evaluations showed profound anemia, an elevated erythrocyte sedimentation rate, and an increased C-reactive protein level with polyclonal hypergammaglobulinemia. Chest radiography, computed tomography (CT), and positron emission tomography-CT scan demonstrated diffuse lung infiltration with multiple cystic lesions and multiple lymphadenopathy. In addition to these clinical laboratory findings, bone marrow, lung, and lymph node biopsies confirmed the diagnosis of idiopathic MCD (iMCD). Siltuximab, an interleukin-6 inhibitor, and glucocorticoid therapy were initiated. The patient has been tolerating the treatment well and had no disease progression or any complications in 4 years. Herein, we report this case of human herpesvirus-8-negative iMCD-associated DPLD accompanied by multiple cystic lesions, multiple lymphadenopathy, and polyclonal hypergammaglobulinemia with elevated immunoglobulin G (IgG) and IgG4 levels. We recommend a close evaluation of MCD in cases of DPLD with hypergammaglobulinemia.