Since SCLC is classified with neuroendocrine tumors, immunohistochemistry is very important in the diagnosis of SCLC, especially some neuroendocrine markers, such as Synaptophysin (Syn), Chromogranin A (CgA) and CD56 (an alias for neural cell adhesion molecule 1) (12). The gene discussed is SYP; the disease is neuroendocrine neoplasm.