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

Area of Science:

• Pulmonology
• Infectious Diseases
• Oncology

Background:

• Multicentric Castleman's disease (MCD) is a rare lymphoproliferative disorder.
• Patients with MCD are often immunocompromised and susceptible to opportunistic infections.

Observation:

• A woman in her 60s with suspected MCD on prednisolone presented with cough and malaise.
• Chest CT revealed diffuse lung lesions, initially presumed to be MCD exacerbation.

Findings:

• Biopsy confirmed MCD and revealed *Cryptococcus neoformans* in the alveolar space.
• *C. neoformans* infection can present with diffuse lung infiltrates, mimicking MCD flares.

Implications:

• Clinicians should consider opportunistic fungal infections like cryptococcosis in immunocompromised patients with suspected MCD exacerbations.
• Accurate diagnosis is crucial as treatment differs significantly between MCD and *C. neoformans* infection.