A Wolf in Sheep's Clothing: A Sporadic Juvenile Polyp of the Colon Harboring an Intramucosal Adenocarcinoma.

We describe a solitary peduncolated polypoid lesion with a bilobated head in the transverse colon mucosa of a 51-year-old Caucasian man. Histologically, the lesion was consistent with juvenile polyp (JP), but showing a few dysplastic glands and a focus of intramucosal adenocarcinoma. This finding suggests that, at least in adults, even the sporadic JPs might carry an inherent potential for malignancy, which has so far only been pointed out for syndromic lesions. Additionally, we observed p53 overexpression in both the dysplastic lesions and in the invasive cells but not in the remaining epithelium. We can argue that p53 immunohistochemistry may be helpful in differentiating hyperplastic regenerative atypia of the epithelium, frequently found in JPs, from true dysplasia, a much more rare change in the sporadic JPs.