[Organizing pneumonia associated with the use of trastuzumab].

Organizing pneumonia is a clinical and histological condition in which the onset is usually subacute with respiratory symptoms and pulmonary infiltrates. It may be unknown origin (cryptogenic) or associated with other illnesses, infectious diseases or drugs. We present a 60 year-old female patient with a previous history of breast cancer, who was being treated with trastuzumab, an antiHER2 monoclonal antibody. She was diagnosed with casual pulmonary infiltrates that had histological changes compatible with organizing pneumonia. The pulmonary infiltrates disappeared on withdrawing trastuzumab treatment. Due to the increasing use of biological therapies in different medical areas, we believe it is of interest to report this pulmonary involvement attributed to the monoclonal antibody trastuzumab.