The panel of syntaxin 1 and insulinoma‐associated protein 1 outperforms classic neuroendocrine markers in pulmonary neuroendocrine neoplasms

Syntaxin-1 (STX1) is a recently described highly sensitive and specific neuroendocrine marker. We evaluated the applicability of STX1 as an immunohistochemical marker in pulmonary neoplasms (NENs). compared with established markers, including insulinoma-associated protein 1 (INSM1). Typical carcinoids (n = 33), atypical 7), small cell lung carcinomas ([SCLCs] n 30), large 17) were immunostained using tissue microarray for STX1, chromogranin A, synaptophysin, CD56, INSM1. Eighty-four eighty-seven (96.5%) NENs showed positivity. Carcinoids LCNECs typically presented combined strong membranous weak cytoplasmic staining pattern; expression was predominately observed SCLCs. The sensitivity 90% SCLCs 100% typical carcinoids, carcinomas. overall 96.6%, other markers follows: A (85.2%), synaptophysin CD56 (92.9%), INSM1 (97.7%). found to be excellent NENs, specificity surpassing that classic markers. propose panel routine workup NENs.