A 59-year-old post-menopausal woman presents with pelvic discomfort and urinary frequency. A pelvic ultrasound was performed (Fig. 1) that revealed a large mass lesion in the left adnexa. Enhanced pelvic CT (Fig. 2) confirmed the lesion and better revealed its location without the pelvis.
What’s the most likely diagnosis of the left pelvic mass lesion and what’s the next step?
a) exophytic fibroid, refer to gynecologist
b) ovarian dermoid tumour, refer to gynecologist
c) large rectocele, refer to general surgeon
d) malignant ovarian mass, surgical consult and metastatic workup
e) benign ovarian cyst, follow-up US in 1 year
e) benign ovarian cyst, follow-up US in 1 year
The ultrasound image (Fig. 1) reveals a 7-cm discrete round uniformly hypoechoic/anechoic mass lesion with through transmission, consistent with a large simple cystic mass lesion, most likely ovarian in origin by location alone. On the CT scan, the mass lesion has similar CT density as the bladder situated more anterior, again in keeping with a fluid-filled mass. No associated calcification, fat, mural nodules or other complex features.
You likely were not expecting that answer were you? Combined with ultrasound follow-up in 1 year? Not long ago I would have seen this lesion and recommended direct referral to a gynecologist for surgical removal. In September 2010, a landmark article (see references) was published discussing the management of asymptomatic ovarian cysts identified by ultrasonography (US), written as a consensus statement emanating in conjunction from both Radiology and Obstetrics and Gynecology societies. The article detailed guidelines for action (or relative inaction) based on ovarian cyst size, internal characteristics, and patient age (see Table 1). It’s slowly catching on with imaging departments and being accepted by gynecologists, who will likely be relieved when their offices aren’t filled with patients referred for 2–3 cm simple physiologic ovarian cysts, especially in the pre-menopausal years. There’s some leeway allowed in the recommendations. For the case presented, I’d still likely suggest a gynecology consult, refer to the article and then make the bold suggestion of a 1-year follow-up, especially because the lesion size is at the upper limits of annual follow-up recommendations (see Table 1). In the case presented, a gynecologist referred the patient. She wasn’t entirely asymptomatic; however, the benign symptoms were thought to be related to lesion size. Despite reassuring the patient that the lesion was almost certainly benign, the patient insisted on some form of pathologic confirmation. As such, I performed a transvaginal cyst aspiration under US guidance, revealing benign cyst contents and no cells suggestive of malignancy. After aspiration, the cyst involuted and resolved, no longer visible on follow-up imaging. No surgery was required.
As for the other options provided, an exophytic fibroid would have revealed solid tissue characteristics on US and CT, not pure cystic. Large fibroids may undergo central cystic change from internal necrosis, but not complete cystic transformation. The vast majority of ovarian dermoid tumours will reveal markedly complex internal characteristics on US and CT, often with fluid-fluid levels (serous and sebum), fat tissue, calcification, even teeth, bone and hair. These were not present on the lesion presented. A rectocele results from herniation of rectal tissue through a thin tear in the posterior vaginal wall, allowing the anterior rectal wall to bulge into the vaginal lumen to a greater or lesser degree. Such a lesion would be seen in the midline, lower in the pelvis, in conjunction with the vaginal vault. A malignant ovarian mass lesion will typically exhibit more complex internal features within a cystic mass, which might include thick septations (> 3 mm), solid mural nodules revealing colour Doppler flow, and clumpy areas of wall thickening, with or without associated findings such as complex free fluid, moderate ascites and/or omental seeding and peritoneal nodularity. None of these features were present, thankfully, in the patient presented.
Levine D, Brown D, Andreotti RF, et al. Radiology 2010;256:943-54.
Consensus recommendations for ovarian cyst follow-up
Menstrual age women
Early post-menopausal women (1-5 years without period)
Late menopausal women (> 5 years without period)
* Features may include thin septations (< 3 mm), small mural Ca++, small mural nodules without Doppler flow.
** Features may include thick septations (≥ 3 mm), solid elements with Doppler flow, mural nodules with Doppler flow, associated complex free fluid or moderate ascites, omental nodules.
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