Diffuse cryptococcal pneumonia in multicentric Castleman's disease with elevated serum IgG₄

A woman in her 60s with suspected multicentric Castleman's disease, who was receiving treatment with oral prednisolone, presented to our hospital with mild cough and malaise. Chest CT showed diffuse infiltrative and granular shadows, indicating exacerbation of lung lesions caused by steroid-resistant multicentric Castleman's disease. A video-assisted thoracoscopic lung and mediastinal lymph node biopsy was performed. The biopsy revealed mediastinal lymph node tissue consistent with multicentric Castleman's disease, as well as presence of Cryptococcus neoformans in the alveolar space. C. neoformans infection in immunocompromised individuals may present with diffuse lung lesions and should be noted as a mimicker of acute exacerbation of Castleman's disease.