Sarcomatoid carcinoma of the lung: a clinicopathologic study of 37 cases.

BACKGROUND: Spindle and giant cell carcinomas of the lung are rare subtypes and are regarded as one type of lung carcinoma, termed pleomorphic carcinoma in the Armed Forces Institute of Pathology classification. This classification is different from the World Health Organization classification. METHODS: Thirty-seven cases of sarcomatoid (spindle and/or giant cell) carcinoma of the lung were studied by light microscopy, conventional histochemistry, and immunohistochemistry to establish their clinical and histologic characteristics. RESULTS: The patient population was comprised of 29 men and 8 women ages 33-81 years. Seventeen patients died of their disease and there was no statistically significant difference in patient prognosis between sarcomatoid carcinoma and nonsarcomatoid carcinoma of the lung. Using light microscopy, 5 cases (13.5%) comprised entirely of sarcomatoid components without carcinomatous elements were classified as Group A. In the remaining 32 cases (86. 5%), classified as Group B, carcinomatous components were present (adenocarcinoma [18 cases; 48.7%], squamous cell carcinoma [8 cases; 21.6%], and large cell carcinoma [6 cases; 16.2%]). Sarcomatoid components were divided further into three categories: spindle cell type, giant cell type, and mixed spindle and giant cell type. Immunohistochemically, the sarcomatoid components of all 37 cases were positive for cytokeratins. Statistically, there was no significant prognostic difference between the 37 cases of sarcomatoid carcinoma and 647 cases of nonsarcomatoid, nonsmall cell carcinoma of the lung (P = 0.8537). CONCLUSIONS: The sarcomatoid portions in all sarcomatoid carcinomas in the current study showed an epithelial differentiation, and there was no apparent difference in biologic behavior between sarcomatoid carcinoma and ordinary lung carcinoma.