Rare case of endometrioid adenocarcinoma arising from cystic adenomyosis

Few reports on malignant transformation of adenomyosis are available, and endometrioid adenocarcinoma arising from cystic adenomyosis is further rarely reported. We report a case of a 67-year-old asymptomatic woman who was referred to our hospital for evaluation of a cystic lesion in the pelvis, which had been diagnosed as cystic degeneration of leiomyoma for 3 years. Magnetic resonance imaging revealed a cystic mass measuring 11cm in diameter, which was contiguous with uterine myometrium. The lesion contained solid areas enhanced on gadolinium-enhanced T-1-weighted imaging. Transabdominal simple total hysterectomy with bilateral salpingo-oophorectomy was performed. Pathological examination revealed endometrioid adenocarcinoma arising from cystic adenomyosis. The patient underwent six courses of adjuvant combination chemotherapy with paclitaxel and carboplatin. No metastasis or recurrence has been demonstrated for 16 months following surgery. Our case demonstrates that cystic adenomyoma possesses the risk of malignant transformation, indicating the importance of long-term follow-up with imaging examination.