Endocervical adenocarcinoma in situ presenting in fundal endometrial polyp: the mother of all skip lesions.

A 38-yr-old woman, with a previous history of low grade squamous intraepithelial lesion in the cervix, presented with heavy menstrual bleeding. At hysteroscopy, a fundal polyp was removed from the right cornu which displayed many glands lined by atypical, mitotically active epithelium with features characteristic of endocervical adenocarcinoma in situ (AIS) of intestinal subtype. Subsequent cervical liquid-based cytology and colposcopically directed biopsies revealed no causative lesion, but residual PreservCyt from the ThinPrep vial tested positive for high risk HPV type other than HPV 16 and 18. Further biopsies from the endocervical canal and base of the resected polyp showed intestinal type AIS, while all those from the intervening anterior and posterior endometrial lining exhibited normal endometrium only. Genomic DNA extracted from the endometrial polyp and second set of endocervical biopsies tested positive for HPV 31, an uncommon cause of endocervical glandular neoplasia. Endocervical AIS typically arises in the transformation zone but may be found exclusively in the endocervical canal and rarely as high as 30 mm from the ectocervix. Contiguous spread into the lower uterine segment is known to occur, as are proximate so-called skip lesions. However, finding a 'skip' lesion 80 mm from the transformation zone poses an interesting pathogenetic conundrum as well as a therapeutic dilemma in a young patient desirous of retaining fertility. Issues relating to pathogenesis include necessary metaplasia of the endometrial glandular epithelium to 'susceptible' endocervical type epithelium within the polyp or metastatic implantation of transformed endocervical glandular cells onto the polyp. The current management plan involves regular hysteroscopic surveillance of the uterine cavity.