[Central and peripheral type small cell carcinoma of the lung--histologic, immunohistochemical, and clinical...

In 17 cases of resected small cell carcinoma of the lung, there were 4 cases of central type and 13 cases of peripheral type. Histologic subtypes were classified into oat cell carcinoma (OAT), intermediate cell type (INT), and small cell carcinoma with large cell component (SC/LC). SC/LC was divided according to the criteria of Radice et al. Immunohistochemically, gastrin-releasing peptide (GRP) and neuron specific enolase (NSE) were used as markers for neuroendocrine cells, and keratin and secretory component (SC) were used as markers for epithelial and gland epithelial cells, respectively. Histologically, 4 cases of the central type were divided into 3 cases of INT and one case of SC/LC. Thirteen cases of the peripheral type were divided into 3 cases of OAT, 6 cases of INT, and 4 cases of SC/LC. SC/LC was more frequently seen in the peripheral type than in the central type. Immunohistochemically, there was no difference in the frequency of positive staining for GRP and NSE between the central and peripheral types, but positive staining for keratin and SC were more frequent in the peripheral type than in the central type. Three cases who survived more than 3 years were histologically divided into two cases of INT and one case of SC/LC. Immunohistochemically, these 3 cases showed positive staining for GRP or NSE, but also showed positive staining for keratin or SC. Our results showed that some of the peripheral type small cell carcinoma of the lung had histologic and immunohistochemical features which were different from those of typical small cell carcinoma. Long survival time after resection in some of the peripheral cases might be due to these features.