Bronchiolitis obliterans with organizing pneumonia and cold agglutinin disease associated with phenytoin hypersensitivity syndrome

Phenytoin hypersensitivity syndrome (PHS) is a rare delayed hypersensitivity reaction which occurs following exposure to phenytoin sodium. Pulmonary involvement is uncommonly described. Herein is reported the first case of histopathologic bronchiolitis obliterans organizing pneumonia (BOOP) found on open-lung biopsy in a patient with severe PHS. New onset, clinically significant, cold agglutinin disease was also documented. Hemodynamic parameters mimicking sepsis were present in the absence of significant clinical infection. Rapid, dramatic improvement followed high-dose steroid therapy.