TP53 and neuroendocrine neoplasm: The sheet-like component was morphologically similar to a well differentiated neuroendocrine neoplasm and was immunohistochemically diffusely positive for chromogranin A. This component, as well as the pleomorphic component, which was slightly positive for chromogranin A, also suggested genetic abnormalities in TP53, Rb1, and p16 that are characteristic of NECs [9, 11].