[A case of pulmonary adenosquamous cell carcinoma with thin-wall cavities].

A 68-year-old man was admitted to our hospital because of continuous cough of three months duration and for investigation of a thin-wall cavitary lesion (> 3 cm) in the right upper lung field. Thin-wall cavity (40 x 35 mm) with notch and spiculation was observed in the right S2 on chest CT. A histological diagnosis of pulmonary adenocarcinoma was obtained by bronchoscopic examination, and he was transferred to the Department of Thoracic Surgery where a right upper lobectomy was performed. Subsequently, cavity formation (45 x 40 x 35 mm) was disclosed in the right S2. Most of the surrounding cavity consisted of the components of a well differentiated squamous cell carcinoma with keratinization and slightly different components of a poorly differentiated adenocarcinoma with mucous production. The final diagnosis was pulmonary adenosquamous cell carcinoma and the postoperative histological classification was T2N2M0 (Stage 3A) because of metastasis to the lymph nodes (#4 and #11). A communicating bronchus was histologically identified and we presumed that the thin-wall cavity developed by a check valve mechanism. Although squamous cell carcinoma has been reported to be the histological type, tending to form thin-wall cavities among patients with lung cancer reported to be squamous cell carcinoma, recently an increasing number of such cavities have been reported among patients with pulmonary adenocarcinoma. Herein, we have reported a rare case of histological diagnosis of pulmonary adenosquamous cell carcinoma with cavity formation.