Fatty bronchogram: a sign of cystic teratoma rupture in the lung.

A 47-year-old man was admitted to our hospital for septic fever. Multidetector computed tomography showed a pulmonary cavitated consolidation that was partially filled by low-density material and an interrupted rim of soft tissue in adjacent mediastinum, lining an inhomogeneous fat density area. Lung consolidation presented a bronchogram fluid sign with a -40 Hounsfield unit density value, which indicated a fatty bronchogram. Mediastinal cystic teratoma rupture in the lung was derived from a bacterial infection, with the lipoid material pouring into the lung and its drainage bronchus.