Bronchiolitis obliterans organizing pneumonia mimicking multiple pulmonary metastases.

A 45-year-old woman with no history of cancer presented with a radiological and clinical diagnosis of metastatic tumor in the lungs. On the basis of the findings, the patient underwent an extensive investigation attempting to locate a primary tumor. After an unsuccessful workup, the patient was referred for biopsy, which showed findings of bronchiolitis obliterans organizing pneumonia (BOOP). This case illustrates that the clinical, roentgenographic, and CT findings of BOOP are nonspecific and in some cases can be confused with those of metastatic tumor in the lungs.