Subserosal cystic adenomyoma presenting as severe dysmenorrhea: a case report

Cystic adenomyoma is a rare focal variant of adenomyosis characterized by a cystic cavity lined by endometrial glands and stroma within hypertrophic smooth muscle. Subserosal pedunculated forms are exceptionally uncommon and may mimic uterine or adnexal masses, leading to diagnostic challenges. We report a case of a 28-year-old nulliparous woman presenting with severe progressive dysmenorrhea refractory to medical therapy since adolescence. Her medical history was notable for a previous right salpingo-oophorectomy performed ten years earlier. Pelvic ultrasound demonstrated a well-defined 6-cm cystic lesion arising from the uterine wall via a subserosal stalk, without communication with the endometrial cavity. Diagnostic laparoscopy identified a pedunculated mass originating from the uterine serosal surface, which was completely excised. Gross examination revealed an encapsulated cystic lesion containing hemorrhagic fluid. Histopathological analysis showed interlacing smooth muscle bundles with embedded endometrial glands and stroma, confirming cystic adenomyoma. The patient experienced complete resolution of symptoms with normal menstrual cycles at 4-month follow-up. This case illustrates an exceedingly rare pedunculated subserosal cystic adenomyoma manifesting as severe dysmenorrhea. Recognition of this entity is important in young women with persistent menstrual pain and normal uterine cavity morphology. Accurate diagnosis relies on imaging correlation, surgical evaluation, and histopathological confirmation, while laparoscopic excision remains as a treatment of choice.