Neuroendocrine differentiation in non-small cell lung carcinomas.

The immunohistochemical expression of ten neuroendocrine and neural differentiation-related antigens in 200 specimens from patients with surgically resected non-small cell lung carcinomas were evaluated. Poorly differentiated adenocarcinomas and undifferentiated large cell carcinomas showed the highest percentage of positive samples (30%-60%) for the markers evaluated with diffuse and intense immunostaining. Poorly differentiated squamous carcinomas bronchioalveolar adenocarcinomas, and giant cell carcinomas showed a lower percentage of positive samples (20%) with moderate immunostaining. Well differentiated tumors were very rarely positive for the neuroendocrine markers. It is concluded that neoplasms positive for the neuroendocrine markers can be considered as non-small cell carcinoma with neuroendocrine features, even if they do not have the histological appearance of neuroendocrine lung neoplasms.