At this time, his PPD test and cultures of sputum were negative and his chest x-ray film and CT showed a round, well-defined, large right lower lobe mass (Fig 1). Contrast medium was administered during the study and failed to demonstrate any arteriovenous connection. A right lower lobectomy was performed.

Fathologic Study

At the posterior basal segment of the resected lobe, a spherical mass extended from the pleura into the pulmonary parenchyma (Fig 2). The visceral pleural surface covering the mass contained multiple dark red cysts measuring 0.2 to 0.5 cm in diameter. The cut surface of the mass showed it to be 4.5 cm in diameter, round and well demarcated. It had a spongy consistency and was made of numerous cystic spaces filled with blood-stained fluid. review

Histologic examination revealed a network of channels, most of which centered around the bronchioles. Some were present in the septa and in the subpleural region. There was no capsule separating the lesion from the surrounding parenchyma. The channels varied in size, and their walls were of variable thickness. The inner surface of the channels was lined by flattened endothelial-looking cells (Fig 3). The walls were composed of connective tissue in which, in some areas, groups of smooth muscle fibers were present.

Figure 1

Figure 2

Figure 3
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