Bronchiolitis obliterans organising pneumonia syndrome presenting with neutrophilia in bronchoalveolar lavage fluid after breast-conserving therapy.

A 61-year-old female presented with a dry cough and fever 4 months after tangential radiation therapy (RT) following conserving surgery for breast cancer. Chest radiography and CT demonstrated consolidation with air bronchogram outside the irradiated area. Neutrophil granulocytes were abundant in bronchoalveolar lavage fluid (BALF) (39.6% of total cells), and transbronchial lung biopsy revealed organising pneumonia (OP) histologically. Antibiotic therapy had no effect, but corticosteroid therapy brought about clinical improvement. Her condition was diagnosed as bronchiolitis obliterans OP (BOOP) syndrome. Lymphocytic BALF has been identified as a characteristic of BOOP syndrome induced after RT for breast cancer. The BALF in this case, however, was neutrophilic. In our analysis of differential cell counts in the BALF of 24 patients with BOOP syndrome, the BALF was neutrophilic (>5%) in 16 (76%) cases, and the neutrophilia was severe in some of those patients.