Chronic course of human T-cell lymphotropic virus type-1-associated bronchioloalveolar disorder diagnosed using transbronchial lung cryobiopsy

Human T-cell leukemia virus type 1 (HTLV-1)-associated bronchioloalveolar disorder (HABA) refers to a group of diseases characterized by specific lesions in the bronchioloalveolar region caused by HTLV-1 infection. We report a case of chronic obstructive ventilatory impairment due to HABA, which had long been diagnosed and treated as bronchial asthma with inhaled therapies. The definitive diagnosis was established based on histopathological findings obtained via a transbronchial lung cryobiopsy. Chronic lymphocytic infiltration, bronchioloalveolar remodeling, and peripheral airway narrowing due to bronchus-associated lymphoid tissue hyperplasia were identified as factors contributing to the progressive obstructive ventilatory defect. This case highlights the utility of transbronchial lung cryobiopsy as a valuable diagnostic tool for HABA, especially when imaging findings are atypical for common obstructive lung diseases. In this case, inhaled corticosteroids were observed to lead to symptomatic improvement, and the addition of long-acting β2-agonists and long-acting muscarinic antagonists may have been beneficial for recurrent symptoms.