We present a case of a 10-year-old girl who was diagnosed by a physician with bronchial asthma five years earlier. She was treated with an inhaled corticosteroid and oral administration of a leukotriene receptor antagonist. She was referred to our department after five years of treatment as her wheezing did not improve.

Chest auscultation detected expiratory wheezing, and computed tomography (CT) revealed fluid retention in the paranasal sinuses. Chest radiograph and CT showed nodular shadowing.

Hematological examination revealed an increase in the cold aggregation rating. Based on these findings, the patient was diagnosed with diffuse panbronchiolitis (DPB) and oral administration of clarithromycin was initiated. After five months of treatment initiation, there was improvement in her respiratory symptoms and respiratory function. Currently, the patient is being followed up without treatment and is free of respiratory symptoms or function deterioration.

If symptoms of cough or wheezing do not respond to prolonged treatment for asthma, DPB should be considered in the differential diagnosis list.