"Tree in bud" attributable to organising pneumonia

Thorax

Learning point

  • Cryptogenic OP may rarely present as a small airway-predominant disease causing severe airflow limitation and a ‘tree in bud’ pattern on HR-CT.

  • A 19-year-old man presented with dyspnoea, a non-productive cough and subfebrile temperature. Chest radiography showed a diffuse nodular pattern and a pneumomediastinum. HR-CT revealed a diffuse ‘tree in bud’ pattern (figure 1). An infectious bronchiolitis was suspected. Despite treatment with moxifloxacin he developed hypercapnic respiratory failure requiring mechanical ventilation. Extensive microbiological investigations did not reveal a pathogenic microorganism. Continued treatment with antibiotics, low-dose steroids and neomacrolides was not effective, and an open lung biopsy was performed. Histology showed an organising pneumonia (OP) with extensive endobronchiolar granulation tissue (figure 2). The treatment was converted to high-dose steroids upon which the patient improved rapidly. Spirometry performed shortly after intensive care discharge revealed a severe airflow limitation (FEV1 40% predicted)....