An atypical case of adenomyosis coexisting with simple endometrial hyperplasia: A case report

Rationale: Adenomyosis and simple endometrial hyperplasia are common benign gynecological conditions. However, atypical presentations with extreme endometrial thickening and associated diagnostic challenges have rarely been reported. Patient concerns: A 27-year-old woman presented with a 13-year history of menstrual irregularity and endometrial thickness of 7.0 cm on ultrasonography. Magnetic resonance imaging (MRI) revealed an enlarged uterus and a 7.9 cm intrauterine mass (T1 isointense, T2 hyperintense, diffusion-weighted imaging high signal) with junctional zone interruption. Interventions: Taking into account the patient’s reproductive needs and the fact that hysteroscopy couldn’t completely remove the contents of the uterine cavity, an open surgery was used for diagnosis and treatment. Diagnoses: Pathological examination led to the diagnosis of adenomyosis combined with non-atypical endometrial hyperplasia. Outcomes: After 6 months of postoperative gonadotropin-releasing hormone agonist (GnRH-a) treatment, the patient achieved regular menstruation. During 10 years of follow-up, she had 2 natural pregnancies and delivered 2 full-term infants via cesarean section. Lessons: This case highlights that adenomyosis can present with an extremely thickened endometrium, an intrauterine mass and the absence of typical dysmenorrhea. Combined surgery and GnRH-a can achieve long-term symptom control and successful pregnancies, supporting fertility-preserving management in similar young patients.