Dome-shaped lesion on chest radiograph: retroperitoneal abscess dissecting through the posterior chest wall.

A 50-year-old man with an 8 x 4 cm mass on the posterior chest was found to have a large retroperitoneal abscess due to Klebsiella pneumoniae. The abscess dissected through the right lower lobe of the lung and the posterior chest wall to produce a subcutaneous mass. The source of the posterior chest wall mass appeared to be a perinephric abscess. A dome-shaped lesion above the right hemidiaphragm on chest radiograph resolved immediately with surgical drainage, suggesting that an abscess should be a prime consideration when one observes such a lesion on a chest film.