Video
Making a Diagnosis of Immune Thrombocytopenia
Opening their discussion on immune thrombocytopenia (ITP), expert panelists review criteria for diagnosis and highlight differences between adult and pediatric populations.
Transcript:
Morey Blinder, MD: Hello, and welcome to this OncLive Peer Exchange®, advances in the treatment and management of immune thrombocytopenic purpura, or ITP. I’m Dr Morey Blinder from Washington University School of Medicine in St Louis and Siteman Cancer Center [Missouri]. I’m an adult hematologist with a focus on classical hematology, and I will help moderate this program. I have the distinct pleasure of having 3 colleagues join me today in this virtual discussion. We’ll go ahead and introduce everybody in alphabetic order. Please introduce yourselves. Dr Landau?
Daniel Landau, MD: Hi, everybody. Thank you for inviting me to be a participant in today’s program. My name is Dr Danny Landau. I’m a hematologist oncologist out of Orlando, Florida. I function as the section chief at the Orlando Health Cancer Institute. I have a focus on hematologic conditions, benign or malignant. Certainly, I have a large population of patients with ITP and I’m always delighted to interact with my colleagues and throw around ideas and network. It’s always a delight to be here. Thank you for having me.
Morey Blinder, MD: Howard?
Howard Liebman, MD: Hi, I’m Dr Howard Liebman. I’m at the University of Southern California Keck School of Medicine in the Norris [Comprehensive] Cancer Center, [Los Angeles]. I’m a nonmalignant hematologist, and I focus predominantly on thrombosis and autoimmune blood diseases. I’m joined in a large cohort of 4 other nonmalignant hematologists who cover a broad range of the topics. I’ve had a long interest particularly in ITP, and some of the so-called secondary forms of ITP. Although in my opinion, there’s no such thing as secondary ITP.
Morey Blinder, MD: Cindy?
Cindy Neunert, MD: Hi, I’m Dr Cindy Neunert. I’m a pediatric hematologist at Columbia University [Herbert Irving Comprehensive Cancer Center] in New York, New York. I’m the section head of hematology there and my focus has been on hemostasis and thrombosis with an interest in patient-related outcomes and immune thrombocytopenia. Specifically, how treatments and treatment approaches impact the patient overall, not just from the standpoint of their laboratory values.
Morey Blinder, MD: Well, thank you all for participating. Today, we are going to discuss new data on ITP treatment and management and help put this data into perspective as to how it may impact our practice. In addition, we’ll be discussing some other issues for which we’re still looking for answers, and we’ll cover this in 4 segments.
Let’s get started on our first segment, which briefly covers ITP disease background, and review some of the first-line treatment options. Let’s talk about ITP, what causes ITP and how is it diagnosed. We’ll discuss a little bit about how patients with ITP are stratified by risk and how is the ITP landscape changing over time. What’s been happening in terms of the incidence and prognosis? We do see a lot of patients with thrombocytopenia. It is still, at times, a challenge to make the diagnosis of ITP. There’s still no diagnostic standard. I think the stratification by risk often relates to the severity of thrombocytopenia, but I would like to hear other opinions on the initial diagnosis of ITP. Howard, would you like to talk about the initial diagnostic algorithm that you use?
Howard Liebman, MD: Well, I think the first approach is not only looking at the CBC [complete blood count] and defining whether there are other cell groups involving anemia, exclusive of the fact that someone who has severe thrombocytopenia, particularly a woman [who] may have excessive menstrual loss and have evidence of iron deficiency anemia, but also looking if the indices otherwise are abnormal. A patient might have macrocytosis, and back of that also the white [blood cell] count and differential. Finally, obviously, the platelet count. I might bring up an interesting and important aspect that people don’t look at often. That’s the mean platelet volume, MPV. There’s good data, particularly from the Europeans, that MPVs above 12.4 could often suggest another diagnosis, being potential congenital thrombocytopenia. I mention that because I learned when I was a medical student there are big platelets in ITP, but the majority, over 90% of them, their MPVs are down. Then essential to that is you have to look at the blood smear. You have to rule out platelet clumping. You have to look if there are other abnormalities in the red cells and the white cells. I think a failure to look at blood smears is often the failure that many clinicians do due to time and other reasons. You can always, if you feel uncomfortable, have a pathologist look at the smear for you. Then after that, now you have to look and have a good history to exclude possible drug interactions that might cause thrombocytopenia and new medications and other symptoms that might suggest another diagnosis. I think that’s really the starting point for the assessment of the patient.
Morey Blinder, MD: Howard, when you see a patient with macrothrombocytes, do you think that maybe the thrombocytopenia is pseudothrombocytopenia because they’re miscounted, or do you like to check that, as well?
Howard Liebman, MD: Well, I think we always do that. That goes along with looking at the smear. Patients who have large platelets, macrothrombocytopenia, often are individuals that have underlying congenital defects. As a referral center for ITP, we’ve in the last 4 months, I and my colleagues, one being Dr Ilene Weitz, [MD], have discovered at least 3 new genetic forms of thrombocytopenia in the Bernard-Soulier complex. She has a whole large family cohort now that she’ll soon be publishing of individuals from Cambodia. I think that really means, yes, I’ve got to look at that smear beyond just the MPV. Interestingly enough, sometimes the MPV is not red. What that reflects is that there’s such a distribution of platelets that they run into the red cell imaging because when they calculate the MPV, they’re looking at all particles going through the culture analysis. Usually, there are 2 curves, an early curve, which are platelets, and then a later curve that becomes the red cell size. When you have a continuous elevation of platelets, some larger, or even larger than platelets, you cannot define the MPV and they’ll just leave it. I have a lot of those pictures I show my fellows, and with most of the modern culture machines, unless they do platelet analysis, cannot define the MPV. Sometimes that dependent will place it, cannot define [it] due to interfering substances, but often that’s because there’s a continuous line of platelets leading to the size of red cells.
Morey Blinder, MD: I’d like to ask Cindy her perspective as a pediatric hematologist and maybe discuss some of the other aspects that might be triggering an ITP viral syndrome, or maybe something like CVID [common variable immunodeficiency]. What are your thoughts about those issues?
Cindy Neunert, MD: Certainly, there are a lot of similarities between pediatrics and adults, but there are also quite a few differences. For us, ITP very similarly remains a diagnosis of exclusion. You’re looking for that isolated thrombocytopenia with really no other findings. In children, the typical course is quite different than in adults. The majority of children will get better much faster, but for those children that don’t resolve their ITP, we start thinking about it as congenital thrombocytopenia or, to your point, is there some sort of underlying immune dysregulation that really causes a child to have an autoimmune presentation at the age that they did. We’ll start to look to see if we can uncover CVID or any of the other genetic mutations that we now know can be responsible, particularly in the patients that have Evans syndrome, which is where they have ITP alongside 1 other autoimmune cytopenia. In which case, in that setting, a lot of children we’re discovering have some sort of immune dysregulation.
Transcript edited for clarity.
