Pathologic evaluation of uterine leiomyoma treated with radiofrequency ablation.

OBJECTIVE: To explore the mechanism by which radiofrequency ablation (RFA) treats uterine leiomyoma by observing the features of the lesions caused by RFA to leiomyoma tissue. METHODS: Specimens from treated lesions were observed after hysterectomy was performed immediately (acute test) or on the third day (chronic test) following treatment in 2 groups of 30 patients. Histopathologic studies were also performed for all specimens, with untreated specimens as controls. RESULTS: For the acute and chronic tests, specimens from the RFA-treated lesions included the center segment (group 1); the marginal segment (group 2); the segment 1-cm away from the margin (group 3); and the segment 2-cm away from the margin (group 4). In the acute test, group 1 showed a sharply demarcated area of coagulative necrosis that did not express estrogen receptor (ER) or progesterone receptor (PR); group 2 showed a severe hydropic degeneration or necrosis; and group 3 showed regular leiomyoma cells. The expression of ER and PR was significantly less in groups 2 and 3 than in the control group (P<0.05), but ER and PR expression in group 4, which had normal leiomyoma cells, was the same as in the control group (P>0.05). In the chronic test, group 1 showed carbonization and coagulation necrosis without ER or PR expression. There was severe hemorrhage and thrombosis in group 2; hyaline degeneration and tissue granulation in group 3; and mild degeneration in group 4. The expression of ER and PR was significantly lower in groups 2, 3, and 4 than in the control group (P<0.05). CONCLUSION: Radiofrequency ablation might treat uterine leiomyomas by inducing coagulative necrosis and depressing ER and PR expression.