Adenoid basal carcinoma of the uterine cervix: report of two cases with reference to adenosquamous carcinoma.

Adenoid basal carcinoma (ABC) of the uterine cervix is a rare neoplasm with excellent prognosis. Differential diagnosis between ABC and an ABC-like lesion of adenosquamous cell carcinoma (ASC) of the cervix is important due to their contrasting prognosis. Reported herein are two cases of ABC that have been compared with seven ASC exhibiting ABC-like lesions from approximately 2600 resected uterine cervical malignancies diagnosed at Shikoku Cancer Center. The two ABC were incidentally found in the uterine cervix of 69-year-old and 59-year-old Japanese women due to cervical intraepithelial neoplasia grade 3 and to squamous cell carcinoma, respectively. The ABC consisted of infiltrating nests of basaloid cells with low nuclear atypia. The patients remained alive without recurrence for 9 years and 18 months, respectively. An ABC-like lesion was defined as basaloid cell nests simulating ABC, but with some features indicating malignant potential. However, the differential diagnosis was sometimes difficult because two of seven ABC-like lesions were originally diagnosed as ABC. Immunohistochemically, cytokeratin 7 was negative for the basaloid cells of two ABC, but positive for six of six ABC-like lesions of ASC, while cytokeratin 8 was positive for both ABC and ASC. This cytokeratin pattern might provide a good tool for distinguishing between ABC and an ABC-like lesion of ASC when the histological findings are equivocal.