Angioimmunoblastic T-cell lymphoma (AITL) is a type of peripheral T-cell tumour that belongs to the group of non-Hodgkin's lymphomas. Pulmonary lesions can be found in 7%-10% of AITL cases. Imaging findings of the lungs varied; however, immunoblastic infiltration in the lungs is rare. Our patient was a 73-year-old man who received repeated chemotherapy for AITL. Fourth-line therapy using romidepsin controlled the illness, but the patient was hospitalized for dyspnoea and an infiltrative shadow. We performed bronchoalveolar lavage (BAL), and the culture was positive for . The patient was initially discharged with antibiotic therapy, but hospitalized again. Antibiotics were ineffective and the patient required mechanical ventilation. BAL was performed again, after which fluid cytology revealed immunoblast-like atypical cells. Therefore, the patient was diagnosed with pulmonary infiltration due to AITL. Steroid therapy proved ineffective, and the patient died. BAL was used to effectively diagnose pulmonary AITL infiltration.
