Neoplastic cavitary lesions are an unusual type of pulmonary metastases. The authors report two cases of cystic metastatic sarcoma of the lungs that illustrate the clinical, radiologic, and pathologic difficulties encountered in the diagnosis of these lesions. In one patient, multiple small, thin-walled cystic metastases from a lower leg leiomyosarcoma were the only manifestation of metastatic disease. The cystic lesions did not change over an 8-month period and a diagnosis of malignancy was not established until spontaneous pneumothorax, presumably due to rupture of the malignant blebs, prompted a thoracotomy. In the second patient, three thin-walled bullae developed after treatment of noncystic pulmonary metastases from a lowerleg synovial sarcoma. In both patients, the cystic lesions were not evident on chest radiographs, but were well visualized with computed tomography (CT), where they mimicked benign bullous disease. However, additional small cavitary lesions not seen with CT were present in resected pulmonary wedge specimens from both patients. A great degree of variability in the cellular composition of the cyst wall lining in both cases, and a lack of any solid neoplastic tissue masses in one case, led to histopathologic difficulties that required immunohistochemical studies for definitive diagnosis of the metastatic disease. These cases show that pulmonary bullae, even though thin-walled and benign-appearing on CT, may be a manifestation of pulmonary metastases. These lesions must therefore be surgically removed from patients in whom a curative resection of pulmonary metastases is warranted. Cancer 65:1805-1831.1990.
ULMONARY METASTASES are Often Well circum-P scribed nodules that vary in size from miliary lesions to large cannon-ball masses. The antemortem detection of pulmonary metastases depends primarily on radiographic examinations. In an autopsy series,' two thirds of patients with pulmonary metastases had radiologically detectable disease. The remaining patients had histologically proven pulmonary involvement that was not evident From the