CGA and neuroendocrine neoplasm: It is generally believed that positivity for 1 epithelial marker (such as CEA/EMA/panCK) and positivity for at least 2 neuroendocrine markers (such as CD56/NSE/Syn/CgA) are definitive for diagnosis.[6] Among neuroendocrine tumor markers, CD56 is the most sensitive but has poor specificity, CgA has higher specificity but lower sensitivity, and SYN has both good sensitivity and specificity.