CGA and squamous cell carcinoma: Among neuroendocrine markers, CgA, Syn, and CD56 are the most commonly used, with CgA being the most specific and CD56 the most sensitive, albeit lacking in specificity.[23] Mucinous epidermoid carcinomas typically demonstrate 3 distinct cell types: mucus-secreting cells, intermediate cells, and squamous cells, with the latter 2 typically testing positive for P63 and P40.