Transcription
Hello and welcome to another session of digital slide review and sign out. I'm Dr. Louis Hassell, and our program today is part of the Digital Anatomic Pathology, a joint venture with the Digital Pathology Association and Path Presenter.
Our case today comes from the realm of gynecologic pathology, involving a woman who has presented with a pelvic mass and severe hydronephrosis several years after hysterectomy and salpingo-oophorectomy. Excuse me, she did not have a salpingo-oophorectomy; she just had a hysterectomy. Excuse my typo there.
So, here's a representative radiograph showing this rather ill-defined, somewhat variable nodular and soft tissue mass within the pelvis, obscuring the ureters and causing some dilation. Here on the coronal view, we can see that it extends upwards a little bit out of the pelvis; on the right side, it has caused very severe hydronephrosis, which is not as well seen on the left.
A needle core biopsy is obtained, and these are representative images from that sample. As we look here, at first blush, we see a mixture of stromal and fibrous tissue, some vessels, and a fairly bland looking tissue here. Another area shows a little bit more cellular tissue; very low grade appearing, some delicate vasculature, obviously quite congested, and no significant nuclear atypia. There's not a lot of mitotic activity.
In addition, I believe we also have some other characteristic findings. In a couple of areas, we see a little bit more granulation-type tissue with variable cellularity again, alongside a little bit of stromal vascularity. It's a very low-grade appearing tumor.
Oh, here's what I wanted to show; we also have some areas of hemosiderin deposition with a histiocytic response as well. Without knowledge of her prior hysterectomy findings, we thought well, this could be endometriosis or something like that, or a low-grade stromal neoplasm—maybe a GIST or something of that sort.
However, we were concerned about the possibilities of various other sorts of entities. Let's think for a second about what kind of lesions we might consider that could have a delayed recurrence from the gynecologic standpoint.
Certainly, with ovarian neoplasms, we'd think about granulosa cell tumors. This lady was not reported to have had an ovarian tumor; in fact, the ovaries were not even removed at her prior surgery. In the uterus, various stromal tumors can be involved; endometrial stromal sarcomas can have late recurrence, as well as PEComas and smooth muscle tumors. All of these can have local regional recurrence with a variable low-grade appearance. From the vagina and vulvar area, aggressive angiomyxoma is also noted for potential delayed recurrence.
So, of course, we went to our files to see what kind of lesion this patient had. Her hysterectomy was described as having a rather bulky polyp extending into the endometrial cavity. This is a representative section of that. As we look here, we see that this is quite cellular tissue, very blue, and has a very innocuous appearing background with a small vessel appearance. It's composed of fairly low-grade cells with not a lot of mitotic activity. There are slightly less cellular areas and a little bit of heterogeneity over here, but they look fairly similar and likely to be the same type of process, maybe with a bit of slightly different differentiation.
This was worked up and found to be not infiltrative into the myometrium. Here's the base of this polyp, and we can see it's rather bulky, several centimeters across, and as we look at the margin here, this is a very, very smooth and quite sharp margin for this neoplasm.
Accordingly, this lesion was diagnosed as a stromal nodule. It had CD10 positivity, which we see here very strongly positive, interestingly with some variability. In this area, we also classified it as part of the tumor, but we have these areas where it's much more densely positive in this lesion, and it was also positive for hormone markers. Here, we see the staining with estrogen receptor; quite nicely positive in all the nuclei with a fairly moderate to intense staining pattern both here and to a somewhat lesser degree over here, although maybe here we're highlighting a little bit more of the vasculature in the background.
So what is an endometrial stromal nodule and what is a low-grade stromal sarcoma? Well, in fact, these are two lesions that are really, if not twin sisters, at least very close mimics of one another. They have morphological and immunohistochemical features that are very common.
Stromal nodules are usually solitary, well-circumscribed polypoid lesions, and any protrusions off the edges are less than three millimeters. They have been noted to have some cystic areas and may even have necrosis. Whereas endometrial stromal sarcoma is characterized by tongue-like borders with frequent lymphovascular space invasion and a very infiltrative pattern.
Note that both of these tumors are probably hormonally driven and usually are positive for estrogen and progesterone receptors. So of note, in this patient, the ovaries were left behind. Another feature to think about is what's going on in the molecular and immunohistochemical side of things.
These are very common features identified in both; the vascular network is identical, and the morphology is very similar to proliferative pattern endometrium. You can see collagen plaques in areas of hyalinization. You may also see histiocytes and occasional thick-walled vessels, particularly near the borders of some of these, which can be seen.
You may occasionally find infarct-type necrosis with hemorrhage and cholesterol cleft formation; these are not defining of malignancy per se, and occasional heterologous differentiation can also be seen. Of note, the translocation the 17:21 translocation that leads to what's called the JAZF1–SUZ12 fusion is the most commonly identified fusion gene, and that can be found in both of these lesions. This has led many people to suggest that endometrial stromal nodules may be a precursor of endometrial stromal sarcoma.
Now, there are a number of other fusion partners that can be identified as well. Having looked at the material from our case, we got immunohistochemistry, and here we can see nicely that only portions of this biopsy sample represented the stromal neoplasm.
So here's our CD10 staining highlighting those areas of high cellularity, but not the intervening areas which had variable stromal appearance, histiocytes, and so forth. Now of note here, you can see these occasionally slightly larger blood vessels in this lesion.
So how do we explain this? Well, is this a recurrence of the lesion or is this a synchronous development, say, out of endometriosis? We did have some suggestion of the possibility of endometriosis. Certainly, in a situation where the ovaries have been left behind and the patient may have had this propensity towards the JAZF1–SUZ12 fusion, that could have arisen synchronously, or it could have been early occult spread and subsequent growth.
We don't really know, and certainly from a therapeutic standpoint, it doesn't matter at this point. However, our final diagnosis, based on the pattern of spread, was endometrial stromal sarcoma, low grade. In light of the prior stromal neoplasm in the uterus, we suggested that this was recurrent, although as I've noted, the possibility of a synchronous or subsequent primary is also possible.
Well, that's an unusual case for today, but we appreciate you joining us. As always, we welcome your comments. What's the most unusual recurrent neoplasm of the GYN tract that you've encountered? We'd love to hear your thoughts.
As always, please feel free to reach out to me directly if that will be helpful, and of course, subscribe and hit that button so that you'll be sure to catch future releases from our channel. Until next time, until that next release, thanks for joining us.