Misplacement of dysplastic epithelium in Peutz-Jeghers polyps - The ultimate diagnostic pitfall?

Peutz-Jeghers syndrome is characterized by multiple polyps throughout the g astrointestinal tract in association with mucocutaneous pigmentation. Small bowel polyps in the syndrome may exhibit epithelial misplacement, into the submucosa, the muscularis propria, and even the subserosa. The authors dem onstrate two patients in whom there is also misplacement of dysplastic epit helium into the submucosa and muscularis propria of the small bowel. Epithe lial misplacement is recognized to mimic invasive malignancy. Such mimicry is heightened substantially when the misplaced epithelium is dysplastic. Co rrect interpretation of the histologic changes is aided by the use of speci al stains, which demonstrate the associated laminar propria and the lack of a desmoplastic response, and immunohistochemistry, which shows that the mi splaced dysplastic epithelium is accompanied by non-neoplastic mucosa. Ther e is an increased prevalence of gastrointestinal malignancy in Peutz-Jegher s syndrome. However, the presence of perplexing histologic features, caused by epithelial misplacement, especially when some of that epithelium is dys plastic, in small bowel polyps at least has the potential for the overdiagn osis of malignancy in the syndrome.