[Intrapulmonary hematoma diagnosed by magnetic resonance imaging].

We report a case of intrapulmonary hematoma in which magnetic resonance imaging was useful in establishing the diagnosis. A 53-year-old man had bronchial asthma that was well controlled with inhaled beclomethasone dipropionate and salbutamol, and with oral theophylline. A spherical mass was found in the right lower lung field on a chest radiograph taken during a regular physical examination. A CT scan showed a well circumscribed spherical mass, which was attached to an intrapulmonary bullae. Magnetic resonance imaging showed a well-circumscribed mass in the superior segment of the right lower lobe. On a T1-weighted image the mass was hyperintense and had a higher-intensity rim. On a T2-weighted image the mass was hyperintense and had some hypointense areas. We therefore diagnosed intrapulmonary hematoma. Chest radiography 6 months later revealed a substantial decrease in the size of the mass, which supported the diagnosis. As in this case, intrapulmonary hematoma can be difficult to diagnose because of the lack of a history of injury and because of the slow regression. In this case, magnetic resonance imaging was useful in making the diagnosis.