Solitary Peutz‐Jeghers polyp mimicking invasive cancer

Abstract

A 46-year-old man was referred to our endoscopy unit for treatment of a 3-cm pedunculated polyp in the sigmoid colon (Fig. 1). There was a submucosal tumor-like bulging nodule on the stalk, suggesting the possibility of tumor submucosal invasion. Magnified endoscopy revealed that a part of the polyp head had a large tubular (type IIIL) or gyrus-like (type IV) pit pattern and another part showed round to oval (type I) pit pattern. Because there were no type V pits that indicated carcinoma, we made the diagnosis that the polyp was an advanced adenoma and carried out endoscopic mucosal resection. Histological examination showed the upper portion of the polyp consisted of components of arborizing muscular bundles originating from the muscularis mucosae covered with hyperplastic epithelia and tubulovillous adenoma with moderate atypia. The submucosal tumor-like nodule represented mucin-filled retention cysts, some of which were lined with focal aggregations of adenomatous glands (Fig. 2). These findings were compatible with pseudoinvasion of tubulovillous adenoma that arose from a Peutz-Jeghers (P-J)-type hamartomatous polyp.