Atlas of Colposcopy: Principles and Practice

Normal columnar epithelium becomes temporarily white after application of acetic acid. If the acetowhiteness persists and is dense in intensity, glandular lesions should be suspected. The lesion extends into the endocervical canal. There may be abnormal blood vessels on the lesion. The villi of the columnar epithelium become fused to each other.

In adenocarcinoma in situ (AIS) or adenocarcinoma, multiple dense acetowhite areas are typically seen on the columnar epithelium. The columnar epithelium appears as if grated coconut has been sprinkled on it.

Adenocarcinoma is suspected if the dense acetowhite area is on the columnar epithelium, has an irregular surface, and has abnormal blood vessels. The atypical blood vessels of adenocarcinoma are often parallel to each other. However, it is important to note that it is difficult to perform colposcopy of the endocervix. If the cytology suggests a glandular lesion, an endocervical curettage from all 4 sides of the endocervix should be done even if there is no visible lesion. If the HPV test is positive and cytology suggests a glandular lesion, a LLETZ procedure or cone biopsy will need to be performed.

Pure adenocarcinoma in situ cannot be reliably detected by colposcopy. Fortunately, more than half of cases coexist with high-grade CIN, which allows the detection of the abnormality. The lesion is often larger than can be appreciated colposcopically, with the result that the margins of the excised lesions are frequently involved with tumour.