CD274 and celiac disease: Compared with NM‐SBAs, SB‐MCs exhibited an association with coeliac disease (P < 0.001), higher rates of dMMR (P < 0.001), and PD‐L1 positivity by both tumour proportion score and combined positive score (P < 0.001 for both), and a lower rate of CK20 expression (P = 0.024).