[A case of combined squamous cell carcinoma and aspergilloma arising in a cyst wall].

A 76-year-old man in whom interstitial pneumonia and diabetes mellitus had been diagnosed complained of bloody sputum in August, 1998. Chest radiography disclosed irregular shadows in the left lower lung field. Chest computed tomography (CT) scans revealed a cyst and a small nodular lesion in the left S6 segment. Although primary lung cancer was suspected, we did not detect any malignant cells in the transbronchial lung biopsy specimen. CT scans in January 2000 showed a ball-like shadow in the thick-walled cyst in the left S6 segment. Cytologic examination of the sputum and the bronchial lavage fluid from the left B6 revealed squamous cell carcinoma. Left lower lobectomy and mediastinal lymph node dissection were performed. Pathological examination revealed that moderately differentiated squamous cell carcinoma had extensively invaded the wall of the cyst in the left S6 and S10 segments, and was accompanied with aspergilloma. Abnormal thickening of a cyst wall may in some cases suggest the presence of lung cancer.