Immunohistochemical stains were positive for synaptophysin (Syn), chromogranin A (CgA), neural cell adhesion molecule (CD56/NCAM), INSM1, P53, and AE1/AE3 in NEC tissue; but immunohistochemical stains were negative for retinoblastoma (Rb) in mass tissue. The gene discussed is RB1; the disease is neuroendocrine carcinoma.