Hoskoppal D, I Epstein JI, Gown AM, et al. - This study was undertaken to investigate the expression of SATB2 in neuroendocrine neoplasms (NNs) from various primary sites and its utility as a marker in determining the site of origin of these neoplasms. They conducted SATB2 immunohistochemistry on 266 NNs, including lung small cell carcinomas (n = 39) and carcinoids (n = 30), bladder (n = 21) and prostate (n = 31) small cell carcinomas, and gastrointestinal (GI)/pancreatic NNs of various primary sites (n = 145) consisting of well-differentiated neuroendocrine tumours (WDNET)s (n = 124) and poorly differentiated neuroendocrine carcinomas (PDNEC)s (n = 21). SATB2 was found to be a sensitive and specific marker for rectal/rectosigmoid and appendiceal WDNETs and may serve a beneficial diagnostic tool when these sites of origin are considered in the differential diagnosis.