Adenoid basal carcinomas of the cervix: A unique morphological evolution with cell cycle correlates

Adenoid basal carcinoma (ABC) is a rare cervical carcinoma of postmenopausa l women composed of small basal-type (basaloid) cells with focal endocervic al ("adenoid") differentiation. ABCs are associated with high-grade squamou s intraepithelial lesions (HSIL) and contain integrated human papillomaviru s type 16 DNA. However, ABCs have a favorable prognosis and do not metastas ize. Five (5) ABCs were analyzed histologically for a marker distinguishing basal/squamous from columnar (adenoid) differentiation (p63) and cell cycl e activity (Ki-67), and compared with 20 cervical (CC) carcinomas. In contr ast to other CCs, ABCs contained 4 distinct components, including (1) a cla ssic HSIL; (2) a limited invasive component with squamoid maturation, often with a discrete layer of peripheral basal cells; (3) outgrowth of small ba sal cells from either HSIL or squamoid areas; (4) focal endocervical (adeno id) differentiation. ABCs shelved distinct differences in cell cycle activi ty relative to CCs. Ki-67 positivity was high in associated HSILs but remai ned high and concentrated in the suprabasal cells of the invasive squamoid component of ABC. Moreover, proliferative index was variable to sharply red uced in areas of basaloid and adenoid differentiation, in contrast to conve ntional CCs. ABC is a unique neoplasm, not only by its transition through m ultiple phenotypes during invasion, but also by a proliferative index that is high in more mature neoplastic cells during the infiltrative process and reduced with progressive basal differentiation. The precise mechanism unde rlying this unique process of tumor evolution is unclear. However, the post menopausal status of these patients suggests that host factors related to a ging may influence tumor evolution and morphology after HPV 16 infection. H UM PATHOL 31:740-744. Copyright (C) 2000 by W.B. Saunders Company.