Mitotic arrest of endometrial epithelium after paclitaxel therapy for breast cancer.

We report the histopathologic findings in endometrial curettings from a 31-year-old woman with dysfunctional uterine bleeding who had received paclitaxel therapy for breast carcinoma. Paclitaxel, a member of the taxane family of antineoplastic agents that is used in the treatment of breast carcinoma, ovarian carcinoma, and non-small cell lung carcinoma, acts by the simultaneous promotion of tubulin assembly into microtubules and inhibition of microtubule disassembly. The curettings in this case showed fragmented menstrual phase endometrium with striking numbers of mitotic figures. Cell divisions were arrested in metaphase. Glandular epithelial cells showed strong immunoreactivity for bcl-2 and MIB-1. We attribute this marked morphologic effect to paclitaxel-induced mitotic arrest of the endometrium.