[684] Morphology and Natural History of Familial Adenomatous Polyposis (FAP)-Associated Dysplastic Fundic Gland Polyps (FGPs)

Wen Yih Liang, Thomas Arnason, Eduardo Alfaro, Paul Kelly, Muriel Genevay, Robert D Odze, Gregory Y Lauwers. Massachusetts General Hospital, Boston, MA; Brigham and Women's Hospital, Boston, MA

Background: Up to 90% of patients with FAP develop gastric FGPs, which display low grade dysplasia (LGD) in up to 48% of cases. It is unclear if LGD in FGPs in this population carries a significant risk of progression to more advanced neoplasia. The aims of this study were to characterize the morphologic phenotype of dysplasia in FAP-associated FGPs and evaluate their natural history.
Design: All FAP patients with a dysplastic FGP diagnosed from 1999-2008 were identified at 2 hospitals. Slides were reviewed and dysplasia was classified as intestinal, gastric, or mixed phenotype. All follow up biopsies were reviewed. Outcomes were defined as: regression of dysplasia (dysplasia absent at last biopsy); persistent dysplasia (dysplasia of same grade present at last biopsy); progression to a more advanced lesion (diagnosis of higher grade neoplasm, eg. high grade dysplasia [HGD], adenoma, carcinoma); concurrent carcinoma (carcinoma diagnosis <3 months after initial biopsy). Outcomes were compared to FAP patients with FGPs without dysplasia and patients with sporadic gastric dysplasia.
Results: Table 1 shows clinicopathologic features and outcomes in the 3 cohorts. 3 cases of FAP associated FGPs with LGD progressed to 2 adenomas with LGD and 1 intramucosal carcinoma. Dysplasia in FGPs in FAP patients was less frequently associated with intestinal phenotype (p<0.001), HGD (p<0.01), and the finding of concurrent or subsequent carcinoma (p=0.05) when compared to sporadic gastric dysplasia.

 FAP with FGP, no dysplasia (n=15)FAP with FGP with dysplasia (n=24)Sporadic dysplasia (n=56)
Mean age at first diagnosis of FGP in years (range)34.8(20-48)33.6(13-63)-
Mean age at first diagnosis of dysplasia in years (range)-35.1(13-64)65.6(37-95)
Phenotype of dysplasia
Gastric-22(92%)30(54%)
Intestinal-024(43%)
Mixed-2(8%)2(4%)
Grade of dysplasia at diagnosis
LGD-23(96%)39(70%)
HGD-1(4%)17(30%)
Concurrent carcinoma*006(11%)
Outcome
Regression of dysplasia†-8(33%)20(36%)
Persistent dysplasia‡-13(54%)7(13%)
Progression to a more advanced lesion03(13%)7(13%)
Progression to carcinoma01(4%)7(13%)
Mean length of follow up in years (range)3.3(0-10.3)6.1(0.8-12.6)2.6(0-11.3)
Mean number of endoscopies (range)1.6(1-5)5.7(2-22)40 patients had ≥ 1 follow up biopsy



Conclusions: There is a low 5 year risk of progression to more advanced neoplasia in FAP-associated FGPs with LGD. The 3 year endoscopic surveillance schedule recommended for duodenal adenomas in FAP is also reasonable for these patients.
Category: Gastrointestinal

Wednesday, March 6, 2013 1:00 PM

Poster Session VI # 79, Wednesday Afternoon

 

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