Idiopathic Multicentric Castleman's Disease Diagnosed by Pulmonary Histopathology: A Case Report

A 41-year-old woman who presented with lower back pain, stiff shoulders and fatigue was found to have inflammatory laboratory findings and bilateral ground-glass opacities on chest x-ray. High-resolution computed tomography (HRCT) revealed consolidation, a nodular shadow, multiple mediastinal and hilar lymphadenopathy, liver enlargement, and splenomegaly. Lung biopsy showed lymphoid follicles, plasma cells and lymphocyte infiltration along bronchovascular bundles and interlobular septa, and plasma cells infiltrating the interfollicular area. Lymph node pathology revealed regressed germinal centres and an extended interfollicular area with plasma cell infiltration, as well as capillary proliferation with endothelial hyperplasia. There were no specific findings of lymphoma or immunoglobulin G4 (IgG4)-related disease and she was diagnosed with idiopathic multicentric Castleman's disease (iMCD). According to consensus diagnostic criteria, lymph node pathology is required for diagnosing iMCD, but this case demonstrates that lung lesions may also provide diagnostic supportive value.