Carcinoma in situ arising from an adenomyotic cyst

A large adenomyotic cyst is a rare variant of adenomyosis with a benign prognosis. A 72-year-old woman was referred for evaluation of a pelvic mass. A pelvic computed tomography (CT) was performed, which showed a large cystic mass measuring about 10 cm in the greatest diameter with a septation in the uterine myometrium. A cystic adenomyosis or cystic changes of the uterine myoma was suspected. A laparoscopic-assisted vaginal hysterectomy was performed. Pathologic evaluation with positive p53 staining led to the diagnosis of carcinoma in situ arising from an adenomyotic cyst. We report a case of carcinoma in situ arising from an adenomyotic cyst. This is the first reported case describing the malignant transformation of an adenomyotic cyst that has been regarded as benign.