Saddle pulmonary embolus and bronchiolitis obliterans with organizing pneumonia develop simultaneously after first cyclophosphamide, methotrexate, 5FU chemotherapy for breast cancer.

A 62-year-old woman underwent a right mastectomy with axillary node dissection for a poorly differentiated ductal carcinoma. One month later, she underwent a left nephrectomy for a renal cell carcinoma. Two weeks after, she received her first cycle of cyclophosphamide, methotrexate, and 5FU (CMF) as a part of her breast cancer treatment. We describe an unusual case of non-occlusive saddle pulmonary embolus with extensive bilateral deep vein thrombosis and severe bronchiolitis obliterans with organizing pneumonia developing simultaneously after the first CMF chemotherapy for breast cancer.