Isolated adenomyotic cyst associated with severe dysmenorrhea

A case of a 23‐year‐old, nulliparous female with a very rare isolated adenomyotic cyst inducing severe dysmenorrhea was seen. Transvaginal ultrasonographic tomography and magnetic resonance imaging (MRI) showed a 3 × 3‐cm cystic mass within the left anterior wall of the uterine corpus. The cystic space was filled with hyperintense fluid on T1‐weighted images, which was surrounded by hypointense tissue beside the right uterine corpus on T2‐weighted images. The case was preliminarily diagnosed using MRI as having cavitated rudimentary uterine horn. However, hysterosalpingography excluded the possibility of uterine anomaly. A hemorrhagic adenomyotic cyst measuring 3 cm within the left anterior wall of the uterine corpus was surgically removed. There was no evidence of diffuse adenomyosis uteri. Dysmenorrhea completely disappeared postoperatively.