INSM1 and neuroendocrine neoplasm: In the 2022 World Health Organization classification of endocrine and neuroendocrine tumors, the essential diagnostic criteria for neuroendocrine neoplasms in non-endocrine organs include diffuse and intense expression of cytokeratins and either CgA or two other neuroendocrine markers, such as SYP and INSM1 [26].