SYP and neoplasm: In the present paper, the tumor cells followed the characteristic features of SPC, including a solid papillary growth pattern, nuclear palisading around fibrovascular cores, a round to elongated and hyperchromatic nucleus, finely granular eosinophilic cytoplasm, and intracellular or extracellular mucin deposition, as well as positive reactivity for synaptophysin, but without positive reactivity for chromogranin A.