Rare case of giant cystic adenomyoma mimicking a uterine malformation, diagnosed and treated by hysteroscopy.

We describe a case of giant cystic uterine adenomyoma that was diagnosed and treated by hysteroscopy. In a 27-year-old woman with menometrorrhagia, severe dysmenorrhea, and chronic pelvic pain, pelvic ultrasonography revealed an enlarged uterine cavity filled with homogeneous low echogenic fluid content. A large cornual hematometra of 8.0 cm in diameter in a bicornuate uterus was suspected, and this hypothesis was also supported by magnetic resonance imaging findings. On the contrary, hysteroscopy revealed a bilocular huge cystic lesion of the posterior uterine wall that was removed by means of monopolar loop resection. The operative finding and the histopathologic examination confirmed the diagnosis of cystic adenomyoma of the uterus. Hysteroscopy may represent a valid tool for diagnosis and minimally invasive treatment of cystic adenomyoma, including those of large volume. Its use is helpful in differential diagnosis between cystic adenomyoma and uterine malformations as a possible cause of pelvic pain.