TTF-1 staining was seen in 82 of 152 tumor categories including thyroidal cancers (19–100%), adenocarcinomas (94%), neuroendocrine tumors (67%) of the lung, small cell neuroendocrine carcinomas (71–80%), mesenchymal tumors (up to 42%), and thymomas (39%). This evidence concerns the gene TTF1 and thymoma.