[A case of so-called carcinosarcoma of the lung].

A 69-year-old male was followed at our institute for the purpose of hemo-dialization. During follow-up, a tumor shadow (phi 6.5 x 7.0 cm) was found in rt. S5 by chest X-ray. This tumor was diagnosed as squamous cell carcinoma by TBLB. Right middle lobectomy (R 2 a) was performed. Histological staging was pT 2 N 2 M 0, stage IIIa. This tumor was cystic, filled with keratin like substance. Histologically, the cyst wall was composed of well differentiated squamous cell carcinoma and sarcomatous stroma which didn't differentiate into bone, cartilage, muscle, and etc. Immunohistologically, sarcomatous stroma was positively stained by vimentin, negatively by keratin and EMA. This patient survived 7 months with recurrence.