SYN Immunohistochemistry is an assay in pathology diagnosis, SYN is synaptophysin, an immunohistochemical indicator representing neuroendocrine differentiation. SYN immunohistochemistry uses the principle of highly specific binding between antibodies and antigens in the human body to determine antigens such as peptides and proteins in tissue cells, and to localize, qualify and quantify them. SYN immunohistochemistry is commonly used in clinic to diagnose and identify malignant tumors, as well as to determine the primary site of metastatic malignant tumors. For some tumors, it can be further analyzed to improve the pathological typing and histological classification, and to discover tiny metastases, which provides an important basis for the development of treatment plans. Usually SYN immunohistochemistry test needs to pay attention, if the result is abnormal, it is recommended to cooperate with doctors to improve the relevant examination to clarify the cause of the disease.