Primary pulmonary rhabdomyosarcomas: a clinicopathologic and immunohistochemical study of three cases.

Three cases of primary pulmonary rhabdomyosarcoma in adults are presented. The patients were all men between the ages of 57 and 78 yr (mean 67.5). All patients presented with symptoms referable to their tumors, including cough, shortness of breath, pleuritic chest pain, and weight loss. In one patient, a history of tobacco and alcohol abuse was obtained. Anatomically, two tumors were located in the left upper lobe and one in the left lower lobe. Grossly, the tumors ranged in size from 6 to 11.5 cm and were tan-gray, firm masses with areas of necrosis and hemorrhage. Histologically, the tumors were characterized by a spindle cell proliferation admixed with areas showing a pleomorphic cell population with numerous rhabdomyoblasts and areas of hemorrhage and necrosis. Immunohistochemically, all three tumors showed strong positivity with desmin and myoglobin antibodies and negative staining with antibodies against keratin, epithelial membrane antigen, and S-100 protein. All patients had a fatal outcome. Two patients died a few days after admission with respiratory distress; the third one died 2 years after diagnosis with widely metastatic disease. Autopsy findings in all cases disclosed disseminated metastases to multiple abdominal and thoracic organs. Primary pulmonary rhabdomyosarcoma should be considered in the differential diagnosis of poorly differentiated pulmonary neoplasms in adults and should be distinguished from other primary and metastatic sarcomas.