Abstract
We report a rare case of pulmonary adenocarcinoma, presenting as a large pulmonary cyst. A 67-year-old male was admitted to our hospital with an abnormal shadow on a chest radiograph in 2008. Chest CT revealed a pulmonary cyst in the right lower lobe, which was about 8 cm in diameter. Retrospectively, the cyst was recognized on a previous chest radiograph in 2004, when its size was only about 3 cm. We could radiographically confirm the gradual enlargement of the cavity by sequential chest radiograph (2004-2008). A preoperative definitive diagnosis could not be made by a bronchoscopic examination. As the lesion was highly suspicious of a malignant tumor with interlobar lymph node metastasis, surgical biopsy of the cyst wall was performed via the fifth intercostal space. An intraoperative pathological examination with frozen sectioning revealed that the cyst was an adenocarcinoma. He underwent right lower lobectomy and mediastinal lymph node dissection. His postoperative course was uneventful. The thickness of the wall was mainly 2-3 mm in the resected specimen. The final pathological diagnosis was pulmonary adenocarcinoma (pT2N2M0 stage III A), which mainly existed along the entire thin wall, without the formation of a clear nodule.
