Combined carcinoid tumor and squamous cell carcinoma of lung: expanding the spectrum of combined tumors of lung.

Combined lung cancers containing both small cell and non-small cell carcinoma elements are uncommon but well recognized. Lung tumors with neuroendocrine differentiation form a group of histologically distinct tumors with differing clinical behavior ranging from low-grade tumors with good prognosis (typical carcinoid) to intermediate-grade tumors (atypical carcinoid) to high-grade tumors with poor prognosis (small cell carcinoma and large cell neuroendocrine tumors). The authors report clinical findings and pathologic findings in a case of combined carcinoid tumor and squamous cell carcinoma of lung. To the best of the authors' knowledge, this is the first report of such a case in the peer reviewed literature, thus broadening the spectrum of combined lung tumors.