Evaluating Ovarian Masses on Ultrasound Part III

Continuing our discussion of ovarian masses you might encounter when performing ultrasound, which lesions should you diagnose as almost certainly benign? Well, we’ve already said:

• unilocular, thin-walled, anechoic cysts less than 10 cm in diameter in a premenopausal woman;
• unilocular, thin-walled anechoic cysts less than 5 cm in a post-menopausal woman.

So, if we have a patient with a unilocular thin-walled cyst, premenopausal woman, 7 cm, this would most certainly be a benign ovarian neoplasm.

Another indicator would be hemorrhage into a unilocular cyst. Most commonly, hemorrhage occurs into follicular and corpus luteum cysts.

When it occurs into a neoplasm, it is for all intense purposes universally a benign ovarian neoplasm.

So if in fact you can conclude that it is a hemorrhagic cyst, you can state with near certainty that not only is it going to be benign, but that it will almost certainly resolve on its own.

So here are two very typical hemorrhagic cysts with retracting thrombus. If you see that, you can be highly confident that this is both benign, and almost certainly non neoplastic, and will resolve within the next 6 weeks.

If you see old blood in the unilocular cyst or one with 1 or 2 thin, complete or incomplete septations, you can diagnose this as an endometrioma.

So if endometriomas are in the ovary, you see these little follicles in the wall. They have low amplitude echoes, visible wall, acoustic enhancement, and very frequently these little bright reflectors in the wall which make this 46 times more likely to be an endometrioma than any other lesion, so those are good odds.

You are going to want to diagnose specifically if you see something like that, any relatively, thin-walled anechoic cyst with 1 or 2 thin septations.

So, what if you have a pretty large mass but it is predominantly echo free and it has 2 thin septi in it?
That is almost certainly going to be a benign neoplasm.

What about a serous cystadenoma?  Any mass containing high amplitude regional echoes that casts an acoustic shadow is most likley this.  So if we have a mass that’s pretty nasty looking, but it has a region of high amplitude echoes that cast an acoustic shadow, that’s a dermoid.

What about a very funky looking mass that has its own regional high amplitude echoes that cast an acoustic shadow, funky looking, but that’s also a dermoid.

In a third instance, we have a very large mass that’s very weird looking, but it has it’s own regional bright echoes that casts an acoustic shadow, that’s also dermoid. The good news is, dermoids are benign.

In Part IV we will discuss ways of ruling ovarian masses as benign with relative ease depending upon the type of ovarian mass.

Author: Roy A. Filly, MD
Excerpted from:
Diagnostic Imaging Review: For Residents, Fellows and Radiologists
Female Pelvis Section