Endometrial cancer with peritoneal metastasis mimicking deep pelvic endometriosis

A 63-year-old menopausal female patient with complaints of abnormal vaginal bleeding underwent a transvaginal ultrasound (TVUS), which showed marked endometrial thickening. Hysteroscopy-guided endometrial biopsy revealed a grade 3 endometrioid adenocarcinoma. She was then referred to our institution for a magnetic resonance imaging (MRI) examination for staging and treatment planning.

MRI was performed on a 3-Tesla magnet using a protocol with T2-weighted images (T2WI), T1-weighed images (T1WI), diffusion-weighted images (DWI), apparent diffusion coefficient (ADC) map and dynamic contrast enhancement (DCE).

A large endometrial carcinoma was seen on the left side of the uterine cavity, with intermediate signal on T2WI, restricted diffusion on DWI and ADC map, and hypointensity relative to the myometrium at the equilibrium phase of DCE sequences. The lesion invaded more than 50% of the myometrium and presented direct extension to the left adnexa (Fallopian tube and ovary). No cervical stroma invasion was seen, neither were suspicious pelvic lymph nodes identified. Small pelvic peritoneal masses were depicted, with fibrotic reaction and adhesions to the rectum and the uterine torus, similar in aspect and topography to lesions of deep pelvic endometriosis. However, they presented similar signal to the malignancy on T2WI and also restricted diffusion, indicating peritoneal metastasis.

Background

Endometrial cancer (EC) is the most common gynaecological malignancy in developed countries [1-5]. Most cases are diagnosed in early stages, and the majority occur after menopause [2,3,5]. Risk factors include obesity, nulliparity, early menarche and late menopause, hormonal replacement therapy, among others [2,4]. EC is divided into Type 1 cancers (90% of cases), with endometrioid adenocarcinoma as the main type, and Type 2 cancers, with higher grade and more aggressive carcinomas [1,2,4].

Clinical perspective

EC usually presents with abnormal vaginal bleeding in postmenopausal women [1,4]. Its prognosis is good, especially with Type 1 cancers [1-3]. Staging follows the International Federation of Gynecology and Obstetrics (FIGO) system, based on post-surgical findings [6]. Recurrence occurs more commonly with high-grade disease and in patients diagnosed at advanced age [2,3].

Imaging perspective

TVUS is the first examination performed after abnormal vaginal bleeding, detecting abnormal endometrial thickening in postmenopausal women (upper threshold of 4 mm) [1,4]. However, accuracy for evaluation of myometrial depth invasion is suboptimal [4].

MRI is the most accurate exam for EC characterization [1,2]. EC normally presents intermediate signal intensity on T2WI, isointensity with endometrium on T1WI, restricted diffusion (high signal on DWI and low signal on ADC map), and hypointensity relative to the myometrium at the equilibrium phase of DCE (120-180s) [1,3,4].

MRI has an important role in preoperative staging and planning, accurately detecting invasion of more than 50% of the myometrium (stage IB), invasion of the cervical stroma (stage II), of the uterine serosa or adnexa (stage IIIA), of the parametria or vagina (stage IIIB), as well as identifying pelvic and para-aortic lymphadenopathies (stage IIIC). Final staging is later adjusted after surgery [1,3].

Outcome

EC is treated with total hysterectomy and bilateral salpingo-oophorectomy, with abdominal cavity exploration and biopsy of suspicious peritoneal lesions [1,3]. Routine pelvic and para-aortic lymphadenectomy is controversial for stage I EC, but performed for stage II and above [1,3]. Adjuvant radiotherapy is performed in stages III and IV, patients with grade 3 EC and patients with grade 1 or 2 with deep myometrial invasion or other risk factors [3].

Take-Home Message / Teaching Points

EC is the most common gynaecological malignancy in developed countries.

MRI plays an important role in diagnosing EC, as well as in its preoperative staging and surgical planning.

Treatment of EC is mostly surgical, with possible adjuvant radiotherapy or chemotherapy.

Written informed patient consent for publication has been obtained.