The nuclear channel system in endometrial adenocarcinoma exposed to medroxyprogesterone acetate.

The nuclear channel system (NCS), giant mitochondria and subnuclear glycogen form a triad of ultrastructural features observed in normal human endometrial epithelium in response to progestational steroids. Both the giant mitochondria and subnuclear glycogen have been described in endometrial adenocarcinoma, but the NCS has not. This article reports the development of the NCS in adenocarcinoma treated with medroxyprogesterone acetate. Previous studies suggest that the NCS in normal tissue is a response to the acyl group in the 17-beta position of the D-ring of some progestational steroids, such as medroxyprogesterone acetate. Medroxyprogesterone acetate was administered to 12 postmenopausal women with endometrial adenocarcinoma. Hysterectomies were performed 8 to 20 days after treatment. Pretreatment specimens were also obtained on 8 of the 12 patients. Using standard electron microscopy procedures, light microscopy on plastic semithin sections was first used to confirm the presence of tumor. Thin sections of malignant endometrium were prepared and evaluated ultrastructurally for progestational alterations. Abnormal giant mitochondria and subnuclear glycogen were found both before and after treatment. The third element of the triad, the NCS, was not observed in any of the available pretreatment biopsies, but was seen in three of the treated specimens. Thus it appears that the NCS is a response to the given progesterone therapy.