Invasive endocervical adenocarcinoma represents on average 15% of cervical carcinomas and it is associated with the human papillomavirus infection high risk types 16 and 18 in most cases. Its detection has some special features compared to squamous cell carcinoma; glandular precancerous lesions are less known and only adenocarcinoma in situ is diagnosed by consensus among pathologists; adenocarcinoma in situ develops in the squamocolumnar junction by reserve cells but it is hard to be located by colposcopy in the endocervical canal or in the deep glandular recess. Sampling of endocervical cells requires brushes rather than an Ayre spatula. Cytological diagnosis of glandular cells abnormalities is based on the Bethesda System 2001 terminology which redefined endocervical cells abnormalities and also introduced the entity of adenocarcinoma in situ. This entity is characterized by specific morphological features, such as the radial arrangement of nuclei in the periphery, like "at the end of the feathers of a bird's wing"(feathering of cells), images of nuclei palissading or rosette without tumoral diathesis. Glandular cells abnormalities are rare and represent less than 0.1% of all smears and less than 5% of abnormal smears. By improving the collection and the interpretation of abnormal endocervical cells, cytological screening should allow the diagnosis of in situ adenocarcinoma and detection of invasive adenocarcinoma at a very early stage. This will lead to a decrease in mortality from endocervical adenocarcinoma, especially in young women.
