Early invasive adenocarcinoma of the cervix.

BACKGROUND: Adenocarcinoma of the cervix is increasing in frequency. There is a dearth of specific detail concerning the histomorphology, histogenesis, and associated findings in early invasive cervical adenocarcinoma.
METHODS: Forty cases of cervical adenocarcinoma invasive to 5 mm or less were examined in detail.
RESULTS: Mean patient age was 40.9 years. In 78% of the cases, the midpoint of the invasive focus was in the region of the squamocolumnar junction or transformation zone; more than 1 invasive focus was present in 4 cases. Eighty-five percent of cases also had adenocarcinoma in situ (AIS). In 9 of 10 minimally invasive cases, small invasive glands were present in the stroma adjacent to AIS. In some of these, the AIS had preinvasive buds that were still attached. Endometrioid adenocarcinomas were associated with AIS but were located higher in the canal than the more common endocervical type. All three adenosquamous carcinomas were associated with both squamous intraepithelial neoplasia and AIS. Vascular space invasion was observed in two cases, microglandular hyperplasia in four.
CONCLUSIONS: Adenocarcinoma in situ is the precursor to most adenocarcinomas of the cervix with an average interval between clinically detected AIS and early invasion of approximately 5 years, supporting the potential for Papanicolaou test screening to prevent this disease. However, the existence of small carcinomas in the absence of AIS suggests the possibility of rapid progression in some cases. Invasion occurs by budding from or expansion of AIS glands, usually in the region of the squamocolumnar junction. Multifocal invasion is uncommon, as is vascular invasion in early lesions. The endometrioid variant has the same histogenesis as the endocervical type but may arise higher in the canal. The precursor of adenosquamous carcinoma has a similar bimorphic differentiation potential. Microglandular hyperplasia is not related to early invasive adenocarcinoma.