High interobserver variability and frequent overdiagnosis of dysplasia in fundic gland polyps can be improved by detecting atypia on the surface epithelium and an abrupt transition to non‐neoplastic cells

• Published in: Histopathology 2022-01, Vol.80 (2), p.314-321
• Main Authors: Orr, Christine E, Beneck, Debra, Jessurun, Jose, Qin, Lihui, Tyryshkin, Kathrin, Yantiss, Rhonda K, Chen, Yao‐Tseng
• Format: Article
• Language: English
• Subjects: Adenomatous Polyposis Coli - diagnosis; Adenomatous Polyposis Coli - pathology; Adolescent; Adult; Aged; Aged, 80 and over; Dysplasia; Epithelium; Familial adenomatous polyposis; Female; foveolar dysplasia; fundic gland polyp; Gastric Fundus - pathology; Humans; low‐grade dysplasia; Male; Middle Aged; Observer Variation; Overdiagnosis; Polyps; Polyps - diagnosis; Polyps - pathology; Retrospective Studies; stomach; Stomach Neoplasms - diagnosis; Stomach Neoplasms - pathology; Young Adult
• ISSN: 0309-0167; 1365-2559
• DOI: 10.1111/his.14549

Aims Fundic gland polyps (FGPs) arise sporadically and in combination with familial adenomatous polyposis (FAP). Criteria for distinguishing low‐grade dysplasia (LGD) from regenerative atypia in FGPs are not well established. The aims of study were to determine: (i) interobserver variability in diagnosing LGD in FGPs; (ii) bias in diagnosing LGD in FAP patients; and (iii) stringent criteria for LGD in FGPs. Methods and results Five senior pathologists who were blinded to the clinical history reviewed 72 FAP‐associated FGPs and 34 sporadic FGPs. Cases were classified as negative (score = 0) or positive (score = 1) for LGD. Each case was assigned a ‘combined dysplasia score’ (CDS) ranging from 0 to 5 to reflect all five opinions. Fleiss’ kappa showed only moderate interobserver agreement (κ = 0.46). Forty‐one FGPs were classified as negative for dysplasia by consensus (CDS = 0–1), including 10 (24%) originally diagnosed as LGD. In contrast, all 37 cases classified as LGD by consensus (CDS = 4–5) were originally diagnosed as LGD, indicating that overdiagnosis of dysplasia is more common than underdiagnosis (P = 0.0012). Cytological atypia in the surface epithelium and an abrupt transition between atypical and normal‐appearing epithelium were the most sensitive (97% and 100%, respectively) and specific (100% and 98%, respectively) features of dysplasia (P