Histopathological Diagnosis in Soft Tissue Sarcoma
Insights From: Victor Villalobos, MD, PhD, University of Colorado School of Medicine; Saketh Guntupalli, MD, University of Colorado School of Medicine; Shreyaskumar R. Patel, MD, University of Texas MD Anderson Cancer Center; Anthony P. Conley, MD, University of Texas MD Anderson Cancer Center
Shreyaskumar R. Patel, MD: The diagnosis starts with the clinical presentation. Taking one’s history and conducting a physical exam becomes relevant. The next step is a radiologic workup. The difficulty, here, is that so many people are going to have lumps and bumps here and there. There can be mosquito bites that feel like they’re big, and so on, and so forth. So, I think clinical judgment will have to prevail to sort of figure out as to which ones require some radiologic imaging. The radiologic characteristics are fairly representative and fairly diagnostic in determining what is truly a benign lesion versus a malignant lesion. There can always be gray zones. The gray zones will further generate additional workup. The next step would be tissue diagnosis and biopsy.
When we get into the histopathologic diagnosis, the assumption is that there is some radiology guidance. There are suspicious findings on an ultrasound, CAT scan, or MRI. And if there is suspicion of a malignant tumor, sarcoma, in this instance, a purist viewpoint would be that it would be best for that patient to be handled by people who are trained in oncology. It may seem simple to just stick a needle and do a biopsy. Or, many times, in the community, someone says, “Oh, this is a lump. I’m going to just splice it open and take a small piece of tissue.” I think where the needle track is and where the incision is placed clearly have consequences with the ultimate definitive management of the tumor.
Multidisciplinary care, an area which we may emphasize a little later in this conversation, has already started at this stage. The diagnosis is made by different disciplines. The clinicians put their clinical knowledge together. The radiologists contribute the radiology findings. Likewise, you do need the right radiologist or surgeon, whoever is doing the biopsy, to be involved in the process. More often than not, in this day and age, we recommend needle biopsies or core biopsies. Open biopsies are not always necessary. The interventional radiologists need to have some experience and expertise in approaching the lesion directly without compromising the final surgical operation that the patient may need.
When we get a smaller sample, to make the biopsy process easier, and less costly and less cumbersome for the patient and the healthcare system, inherent in that process is the requirement that you have pathology expertise to look at a small sample of tissue and make the diagnosis. This is totally not meant to be disrespectful but, what I do every day, I’m very good at. What I don’t do every day, I’m obviously not very good at. As rare as these tumors are, as we’ve already described, it’s totally unfair, in many ways, for a community pathologist to have to make this diagnosis.
If they’re absolutely stuck with the tissue, in my experience, many of them have the connections, if you will, with some reference laboratories. The tissue would be sent out for a so-called second opinion for final diagnosis. As rare as these tumors are, and as heterogenous as they are, it’s not practical to think that the community pathologist should or would get the right diagnosis.
The histotype does matter. We may get into the treatment-related decisions on this later on. Classifying the tumor as a sarcoma versus a benign tumor, versus a different kind of cancer, within a sarcoma, and, then, trying to assign it the right subtype, which clearly has prognostic and therapeutic implications, becomes very relevant.
I say that it’s not fair to the community pathologist, simply because even at major academic centers, these happen to be rare tumors in the practice of most oncologists, even at university centers. The number of patients that they encounter with this group of diseases may vary from 1 or 2, every 3 to 4 years. It may be 1 or 2, a year. But where there is an established program, we see over a thousand patients in a given year within the group. So, it’s a matter of both experience and expertise. The more they see, the more comfortable they get, and the more likely they are to get to the right diagnosis as early as they can. That’s when the ball gets punted right back to the therapeutic arm of the multidisciplinary team, meaning the surgeons, radiation therapists, and medical oncologist, to say, “What are the prognostic factors for this sarcoma?” And, “What’s the best way to manage this patient?”