Unusual Case of Postmenopausal Diffuse Endometriosis Mimicking Metastastic Ovarian Malignancy

Endometriosis is a common gynecologic condition of the premenopausal years. However, postmenopausal endometriosis is rare (2.2%) and thought to be related to high level of circulating estrogen, especially in hormonal replacement therapy. We present a case of a 69-year-old postmenopausal woman, previously healthy and on no regular medication, with diffuse peritoneal endometriosis and bilateral ovarian endometrioma mimicking metastatic ovarian carcinoma on FDG PET/CT. Both ovarian endometrioma had low-grade activity, but more strikingly, there was diffuse FDG-avid peritoneal dissemination and gross ascites. Endometriosis should not be totally disregarded as a differential diagnosis even at postmenopausal status.