Lung carcinoma with rhabdoid component. A series of seven cases associated with uncommon types of non-small cell lung carcinomas and alveolar entrapment.

Rhabdoid tumor, included in the WHO classification among large cell carcinomas of the lung, is an uncommon type of lung carcinoma with poor prognosis. We report a series of 7 cases of lung carcinomas with rhabdoid component in 10% and 80% of the tumor. The associated tumor was adenocarcinoma in 3 cases--one of them with focal micropapillary pattern--large cell carcinoma in 2 cases, squamous cell carcinoma in 1 case and pleomorphic carcinoma in 1 case. Two adenocarcinomas showed a focal spindle cell component. Micropapillary and pleomorphic types had not been reported before as a component associated with rhabdoid carcinomas. All cases were positive for vimentin, and AE1/AE3 cytokeratin and 5 cases for cytokeratin 7. All cases were negative for muscle and endothelial markers and for chromogranin A. Synaptophysin was focally positive only in one case. Alveolar trapping inside the tumor was present in 3 cases--a phenomenon not well studied in lung carcinomas and also not reported in tumors with rhabdoid component. Five patients died because of the tumor within 2 to 31 months after diagnosis, one of myocardial infarction and only one is alive and disease free 123 months after the diagnosis. In summary, we describe 7 new cases of this uncommon lung tumor with aggressive clinical course, associated with infrequent histological types in nonrhabdoid component and with alveolar trapping, a nondescribed finding.