Shreyaskumar R. Patel, MD: Hello, and welcome to this OncLive Peer Exchange®, “Optimizing Outcomes in Tenosynovial Giant Cell Tumors.” I am Dr Shreyaskumar Patel from The University of Texas MD Anderson Cancer Center. Joining me today in this virtual discussion are my colleagues, Dr John Abraham from Rothman Orthopaedic Institute; Dr Gina D’Amato from Sylvester Comprehensive Cancer Center; Dr Robert Maki from Penn Medicine; and Dr Tae Won Kim from Cooper University Health Care. Today we are going to discuss a number of topics pertaining to the diagnosis and treatment of tenosynovial giant cell tumors [TGCT].

Let’s get started with our first topic. We have divided this into three different subsets. We’re going to start off with the epidemiology and differential diagnosis of tenosynovial giant cell tumors. I’m going to ask one of my colleagues, Dr Abraham, to start us off and provide us an overview of tenosynovial giant cell tumor and the disease state in general. John?

John A. Abraham, MD: Thanks Dr Patel. It’s great to be here and I’m happy to participate. Tenosynovial giant cell tumor is now recognized as one entity. Previously, we didn’t know, as orthopedic surgeons, the difference between tenosynovial giant cell tumor when it happened in a tendon sheath—such as the upper extremity or hand and forearm—or in large joints like the hip and knee, but predominantly the knee. Now we are starting to recognize that this is one entity, and it happens in any synovial-lined area including large joints, small joints, and tendon sheaths.

Thinking about the incidence, some of that information is becoming clearer over time because the original studies on incidence were just looking at what we used to call PVNS [pigmented villonodular synovitis], which we now know as TGCT of a large joint. It is a rare disease, but probably less rare than we originally thought. The numbers in particular for overall incidence of TGCT are probably somewhere in the range of 30 per million person-years, and that includes the hand and upper extremity tenosynovial types and the localized and diffused types in joints.

The most destructive type that we see is the diffuse type in larger joints, and that is probably in the order of four to eight per million person-years. The point is that this is rare, but it’s probably less rare than we originally thought. When we see these patients, there is a slight female predominance. Most of the studies do show a slight female predominance. In terms of age group, we see the full spectrum of ages and that may be due to the fact that there’s a variable presentation. If you have mild disease, you may not seek medical attention until later on in the course of the disease.

Diffuse disease in the large joints does seem to present in younger age groups—20 to 40 years of age—because that diffuse disease does cause quite a bit of disability and that younger age group really notices that disability. If we’re looking at studies in terms of the overall age group, the most common presentation is in the 40- to 60-year-old age group. It does span a wide number of ages.

In terms of what we see when patients come in with this kind of problem, what we see is akin to a synovitis. Patients get a very inflamed and thickened synovium. There are a number of conditions that can cause that, and we usually have to think through which of those conditions could be affecting this one particular patient. Conditions that we see can cause synovitis include infections, and that includes things like Lyme disease. We see synovial disorders such as rheumatoid arthritis or lupus, and tumorous conditions such as TGCT. We have to keep those things in mind when we see these patients and try to figure out which of those things can be affecting the patient. One distinguishing factor is that TGCT most commonly will only affect one area or one large joint. That doesn’t mean it can’t occur in more than one place, but we generally see it in one place.

The common thing that we think of when we think of the symptoms is—we have a buzzword in orthopedics that we use—recurrent atraumatic hemarthrosis. Hemarthrosis is bleeding into a joint and it can happen with trauma, but it can also happen atraumatically. With TGCT, we often see this in the knee or whatever joint is affected. The patient will say, “My knee just blew up,” which means it underwent sudden and severe swelling. Usually that swelling is from blood that comes from the thickened synovium and the very friable tissue of the synovium, which tends to dump large quantities of blood into the joint and then cause the symptoms. The blood is also very irritating to the remainder of the synovium and the rest of the joint, and we can see secondary symptoms from that.

What’s interesting is that in my own clinical practice, I can say that I’ve seen some patients with diffuse disease who have relatively mild symptoms. But in general, diffuse disease causes pretty severe symptoms. The localized form can be interesting because I have seen patients who have a small localized lesion, but who also have the classic recurrent atraumatic hemarthrosis and severe pain and disability and stiffness, even from one small lesion. It’s hard to predict what the symptoms will be based on what we see in terms of how much disease is in the joint. Many times, with those patients—even with a small localized lesion—if I remove that lesion their symptoms can get better.

Shreyaskumar R. Patel, MD: Thanks for getting us off to a great start John. As all of us who have some experience with this disease realize, the patient’s journey likely starts with joint symptoms, as you outlined. I’m sure they go to their PCP [primary care physician] for a little while and receive nonsteroidal treatment for arthritis-related symptom control, but eventually they would make it to the community orthopedic surgeon and then to an orthopedic surgical oncologist. Does that make sense?

John A. Abraham, MD: That’s correct and I think that’s generally how the flow will occur. I think that’s appropriate because we don’t necessarily want to do a million-dollar workup on every patient who comes in with knee pain. It makes sense to treat for the more common things such as arthritis or injuries and then if the patient fails to improve, imaging is indicated whether you’re suspicious of TGCT or some other condition.

Shreyaskumar R. Patel, MD: Fair enough.

Transcript Edited for ClaritySupported by an unrestricted educational grant from Daiichi Sankyo.