SYP and large cell neuroendocrine carcinoma: In detail, large cells, low nuclear/plasmic ratio, vacuolated chromatin with obvious nucleoli, organoid, fenestrated and rosette structures, as well as the identification of neuroendocrine morphology and the expression of at least one of the neuroendocrine markers (chromogranin A, synaptophysin, or CD56) or show endocrine characteristics under the electron microscope, are criteria for the diagnosis of LCNEC.