Development of metastatic endometrial endometrioid adenocarcinoma while on progestin therapy for endometrial hyperplasia.

BACKGROUND

Conservative treatment with progestins is a reasonable treatment option for endometrial complex atypical hyperplasia and, in the experimental setting, for some women with grade 1 endometrial endometrioid adenocarcinoma. The risk of progression to a high-stage endometrial cancer is quite low, with only two previously reported cases in the English literature.

CASE

A 40-year-old woman with endometrial complex atypical hyperplasia diagnosed by dilatation and curettage was managed conservatively with progestin therapy (initially, megesterol acetate; then, a combination oral contraceptive). More than 2 years after her original diagnosis, she developed endometrial endometrioid adenocarcinoma, FIGO grade 2, with lymph node metastasis. The tumor was microsatellite instability-high due to methylation of MLH1 and loss of MLH1 protein.

CONCLUSION

Currently, there are no good criteria for predicting which patients with complex atypical hyperplasia/grade 1 endometrioid adenocarcinoma will optimally respond to progestin therapy. There is some evidence that endometrial complex hyperplasia demonstrating loss of MLH1 protein by immunohistochemistry is strongly related to subsequent or concurrent endometrial cancer, especially tumors of higher grade and stage. In a woman with a biopsy diagnosis of endometrial hyperplasia, evaluation of MLH1 protein status by immunohistochemistry may provide useful information when medical management is being considered.