Case of The Month – May

Case of The Month – May

CT FINDINGS OF A LARGE PROLAPSED ENDOMETRIAL POLYP

A.Oppong- Anane, H Gbadamosi

Korle Bu Teaching Hospital, Accra. Ghana

A 20-year-old female presented to the Radiology Department of the Korle-Bu Teaching Hospital for review of her Computed Tomography scans with a short history of intermittent lower abdominal pain and prolonged post coital bleeding. She had a provisional clinical diagnosis of a prolapsed endometrial polyp

Hard copies of pre and post contrast axial and MPR images of the abdomen and pelvis in soft tissue window acquired from another facility showed the uterus to be slightly bulky and heterogeneous with a demonstrable vaginal mass with the vaginal wall around it. (Figs 1, 2).

Complementary transabdominal ultrasound confirmed the presence of a vaginal mass measuring ~ 7.5 x 5.5 x 5.2 cm which showed a single vessel on Doppler, seemingly arising from the endometrium into the vaginal mass suggesting endometrial origin of the mass (Figs 3, 4).

When it comes to imaging the female pelvis, Transvaginal Ultrasound (TVUS) is the method of choice. Magnetic resonance imaging (MRI) and Computed Tomographic (CT) scan provide important additional information in various disorders. However, in the diagnosis of benign or malignant uterine abnormalities, MRI is superior to CT.1 CT of the abdomen and pelvis plays a pivotal role in the staging of gynecological malignancies. 2  Hysterosalpingography andSonohysterography may play ancillary roles.

 Endometrial polyps are benign nodular protrusions of the endometrial surface. They can often be suggested on ultrasound or MRI studies, but may require saline infusion sonohysterography or direct visualisation for confirmation.3

Endometrial polyps may be sessile or pedunculated. In the latter, the stalk, which usually contains a vascular pedicle, does not normally disrupt the endometrial lining or the endometrial myometrial interface. Histologically, they are composed of stroma of dense fibrous or smooth muscle tissue, vessels, and endometrial glands.3 They are a common cause of vaginal bleeding in pre and post-menopausal women and can occur in 8-36% of patients treated with tamoxifen, due to the pro-estrogenic effects of tamoxifen on the endometrium.3

Although endometrial polyps may be visualised at transvaginal ultrasound (TVUS) as nonspecific endometrial thickening, they are frequently identified as focal masses with surrounding thin hypoechoic halos within the endometrial canal.4, 5 Polyps are best seen at saline infusion sonohysterography and appear as echogenic, smooth, intracavitary masses outlined by fluid. Cystic spaces corresponding to dilated glands filled with proteinaceous fluid may be seen within the polyp. They may also be seen at hysterosalpingography as pedunculated filling defects within the uterine cavity or at T2-weighted MR imaging as low-signal-intensity intracavitary masses surrounded by high-signal-intensity fluid and endometrium. Color Doppler ultrasound(US) can be used to image the vessel within the stalk.5,6,7

Color Doppler can demonstrate vascularity of the endometrial polyp which usually shows a single feeding vessel. The so called “pedicle artery sign” represents a feeding blood vessel of the endometrial polyp.8 Specificity and Negative predictive value are put at 95% and 94%, respectively, when color-flow Doppler is added to grayscale TVUS to identify the feeding vessel.9

Submucoid fibroid or foci of endometrial hyperplasia or carcinoma can mimic a sessile polyp, and foci of atypical hyperplasia are sometimes found within polyps.4 A distinguishing feature could be the presence of multiple feeding vessels which may be shown in endometrial hyperplasia, endometrial cancer and submucous fibroids. Again, uncommonly some endometrial polyps also have multiple feeding vessels.8    A rim like vessel in association with an endometrial lesion should however suggest the possibility of a submucosal fibroid.10,11

Pedunculated submucosal uterine fibroids are usually hypoechoic on ultrasound and tend to have the echogenic endometrium (basalis layer) overlying it confirming their subendometrial location. Another distinguishing feature of pedunculated submucosal myoma from endometrial polyps is the distortion of the interface between the myometrium and endometrium in pedunculated submusosal myoma.  Fibroids tend not to interrupt the endometrium unless they are submucosal in location. Depending on the degree of uterine intracavitary extension submucosal fibroids may distort the uterine cavity. This is best visualised at saline infusion sonohysterography and also appears are filling defects with deformity or enlargement of the endometrial cavity at hysterosalpingography.

On MR imaging, classically, fibroids appear T1 iso to hypointense relative to the myometrium and appear homogeneously hypointense or heterogeneously hyperintense when degeneration is present.12,13

US signs of endometrial carcinoma include heterogeneity and irregular endometrial thickening. These signs are nonspecific and can be seen in endometrial hyperplasia as well as with polyps; polypoid tumors however tend to cause more diffuse and irregular thickening than benign polyps and more heterogeneity than endometrial hyperplasia. A more specific US sign is irregularity of the endometrium-myometrium border, this is suggestive of invasive disease. 14

Endometrial carcinoma usually manifests as a mass, relative to normal endometrium, it is hypo- to isointense on T1-weighted images and hyperintense or heterogeneous on T2-weighted images. Although MR imaging is not helpful particularly in differentiating small endometrial carcinoma from hyperplasia, it is helpful in cancer staging. Tumors are staged on the basis of depth of myometrial invasion. T1-weighted gadolinium-enhanced MR imaging is helpful in demonstrating myometrial invasion because a carcinoma will enhance less than normal endometrium. Again, irregular interface suggests invasion. If the normal low-signal-intensity junctional zone is intact, myometrial invasion can most likely be excluded.15 

Both MR imaging and CT are useful in demonstrating extrauterine spread and lymphadenopathy.

Overall CT is less helpful in investigating abnormalities within the uterus.  On CT, a gross suspicious endometrial mass may be seen as a hypodense lesion, or an enlarged endometrial cavity that often cannot be distinguished from benign lesions. However, CT has better multiplanar spatial resolution that is useful in visualizing the entire pelvic and abdominal cavity for enlarged lymph nodes and gross soft tissue masses, and particularly distant metastases to the lungs.

Treatment of endometrial polyp is usually conservative for asymptomatic patients. If the patient is however symptomatic, then hysteroscopic resection is recommended. All resected polyps should be histologically examined to rule out malignant foci which may be seen in 0.5-3%.3 of cases.

 

Figure 1: Contrast enhanced axial CT scan, demonstrating an enhancing bulky vaginal mass ( white arrow)

Figure 2

Figure 2: Sagittal reformatted contrast enhanced CT scan, demonstrating a poorly enhancing bulky vaginal mass (white arrow).

Figure 3 Transabdominal Ultrasound, Grey scale image, showing a longitudinal view of a the uterus with a hypoechoic vaginal mass (white arrow)

Figure 4: Transabdominal ultrasound of the vaginal mass, grey scale and colour doppler with a ‘ single artery” sign (white arrow) on colour doppler.

Dr A. Badu–Peprah,

Dr Andrea Appau, Dr B Appiah.  

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  2. Chang SJ, Bristow RE, Chi DS, Cliby WA. Role of aggressive surgical cytoreduction in advanced ovarian cancer. J Gynecol Oncol. 2015;26(4):336–42. doi: 10.3802/jgo.2015.26.4.336. [PMC free article][PubMed] [CrossRef]
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