(A) Gastric polyp (4 cm) (arrow) in a 24-year-old man with PJS (STK11 mutation detected). (B) Gastric polyp in PJS (STK11 mutation detected) showing fine branching smooth muscle bands (arrows) between hyperplastic gastric glands. The classic arborizing histology pattern, seen in the intestinal PJS polyps, is often not seen in stomach polyps. (C) Gastric polyps (arrow) in a 25-year-old man with JPS (SMAD4 mutation detected). (D) Gastric polyp in JPS (SMAD4 mutation detected) showing multiple cystic dilated glands (long arrow) in an edematous, inflamed lamina propria (short arrow). (E) Multiple polyps (arrow) in a 36-year-old man with CS (PTEN mutation detected). (F) Gastric polyp in CS (PTEN mutation detected) showing hyperplastic foveolar epithelium (short arrow)-lined polyp with gastric glands embedded in a heterogeneous stroma, consisting of intercalating bands of smooth muscle (long arrow), lymphoid tissue (double arrow), and variable chronic inflammatory infiltrate. (G) Gastric polyp in CCS showing hyperplastic foveolar epithelium (long arrow)-lined polyp with an edematous, inflamed lamina propria (short arrow) mimicking gastric JPS polyps or hyperplastic polyps. (H) FGPs showing dilated glands lined by parietal cells (long arrow) or mucous cells (short arrow).