Table 1.

Syndromic gastric hamartomatous polyps.

	GENETICS	COMMON LOCATION OF POLYPS	ENDOSCOPIC FEATURES	HISTOLOGIC FEATURES	RISK OF GASTRIC CANCER	OTHER FEATURES OF THE SYNDROME
Peutz-Jeghers Syndrome	STK11/LKB1 mutation	Jejunum, colon, stomach	Velvety, papillary surface	“Christmas tree”-like with branching smooth muscle bundles covered by hyperplastic epithelium	15%–29%	Mucocutaneous melanosis, sex cord stromal tumors with annular tubules of ovary, Sertoli cell tumor of testis, adenoma malignum of cervix, other tumors of breast and pancreas
Juvenile polyposis	SMAD4, BMPRA1, or ENG mutation	Colon, rectum, stomach	Smooth, round surface	Dilated mucous-filled glands in an edematous, inflamed lamina propria	10%–21%	May be associated with hereditary hemorrhagic telangiectasia
PTEN hamartoma syndrome	PTEN mutation	Colon, stomach	Variable	Adenomatous, inflammatory, hyperplastic, lymphoid, ganglioneuromatous, leiomyomatous or mixed morphologies	1%	Mucocutaneous hamartomas, Lhermitte Duclos disease, macrocephaly, breast, thyroid and uterine tumors
Hereditary mixed polyposis syndrome	GREM1 mutation	Colon	Variable	Variable	Unclear	Variable, commonly seen in Ashkenazi Jewish family
Cronkhite-Canada syndrome	Likely immune-mediated	Throughout the GI tract	Inflammatory or hyperplastic appearing polyps with abnormal or normal intervening mucosa	Edematous, inflamed lamina propria and tortuous, dilated to cystic glands/foveolae or crypts	Rare	Alopecia, cutaneous pigmentation, onycholysis, chronic diarrhea, etc.