SYP and undifferentiated carcinoma: ONB originates from the upper nasal neuroectoderm and displays neuroendocrine histologist characteristicsI.The immunohistochemical staining of ONB is usually positive for neuroendocrine markers such as synaptophysin, chromogranin, and neuron-specific enolas [2].Therefore, undifferentiated carcinoma should be ruled out through pathological and immunohistochemical identification before making a diagnosis.