Pulmonary non-caseating granuloma in Waldenström macroglobulinemia

Lung involvement is rare in Waldenström macroglobulinemia (WM). We encountered a male patient with WM who complained of breathlessness. Chest X-ray revealed diffuse infiltrative shadow throughout the both lungs. Transbronchial biopsy showed infiltration of atypical plasmacytoid lymphocytes and non-caseating granuloma. We treated the patients with fludarabine phosphate, and both his symptom and X-ray findings were then improved. To our knowledge, this is the first case showing non-caseating granuloma with lung involvement of WM. We discuss a mechanism of non-caseating granuloma formation in this case.