Recurrent Aggressive Angiomyxoma That Responded to the Gonadotropin-Releasing Hormone (GnRH) Antagonist Relugolix

Aggressive angiomyxoma (AAM) is a rare benign mesenchymal tumor occurring in the vulva, vagina, and pelvis; however, it is difficult to treat because it often recurs locally. Since AAM expresses the estrogen receptor (ER) and progesterone receptor (PgR), various hormone therapies have been reportedly effective. Regardless, the efficacy of gonadotropin-releasing hormone (GnRH) antagonists has not yet been reported. We encountered a case of relapsed AAM in which the GnRH antagonist relugolix was highly effective. Although the patient initially underwent surgical resection for the AAM, recurrence occurred 11 months postoperatively. Since the immunohistochemical expression of ER and PgR was positive, relugolix (40 mg/day) was orally administered daily for six months, resulting in significant tumor regression (8.7 cm to 4.6 cm). This is the first report of successful GnRH antagonist treatment for AAM. Although AAM may be difficult to treat, GnRH antagonists are promising candidates for hormone therapy.