Radiation-induced bronchiolitis obliterans organizing pneumonia: a case report and literature review.

Bronchiolitis obliterans organizing pneumonia (BOOP) is defined histopathologically by the presence of a mass of granulation tissue in the bronchiolar lumen, alveolar ducts, and lung alveoli, along with varying degrees of interstitial infiltrate by mononuclear cells and, occasionally, by neutrophils.1,2 Radiographically, radiation-induced BOOP is characterized by pulmonary infiltrates that occur outside of the radiation field.3 BOOP is most often described as idiopathic, but it may also occur secondary to connective tissue disease, medication use, infection, aspiration, and inhalation of toxic fumes.1,3 Risk factors for radiation-induced BOOP have been reported in the literature and include age >50 years and concurrent endocrine therapy in patients with breast cancer treated with breast-conservative therapy.4,5 We report the case of a relatively young woman who developed radiationinduced BOOP while receiving tamoxifen for only 4 months.