Oncologic Emergencies – 6 – Thrombocytosis Erythrocytosis

Oncologic Emergencies PART – 6

(All the articles published in past are available at www.shyamhemoncclinic.com/blog/)

Question:  Last time we discussed Leukostasis. In a case of leukemia, mostly AML, WBC above 50,000 carries a risk of leukostasis – in simple term, slowing of circulation due to too many cells! This can lead to hypoxia, hemorrhage in brain or lungs, other issues. Symptoms are nonspecific. Urgent treatment is required i.e. leukapheresis, hydroxyurea, hydration, avoiding red cell transfusion. Urgent admission is required, even if patient does not look sick, feels good, with normal vital signs. First complication can be intracranial hemorrhage, frequently fatal. This can happen without any warning symptoms, signs. Hence urgent admission and treatment by an expert. What is the next important emergency?

Ans: In the same line, we can think of high platelet count. Much less common than leukostasis however. Extreme high platelet count is a potential emergency, as seen in myeloproliferative neoplasms. Such as seen in Essential thrombocytosis, or sometimes even in Chronic Myeloid Leukemia. I remember such a patient many years ago. He was a known case of CML, who had failed standard treatments at that time i.e. imatinib, and dasatinib. He came with complaint of bleeding gums, on Sunday morning. His platelet count was 32 lac (yes 32,00,000).

Que: Bleeding? With such high platelet count? I would expect thrombosis, not bleeding.

Ans: Well, that was the interesting and more frightening part in this patient. Patients with extreme high platelet count may develop Acquired von willebrand disease. Very high platelet count adsorbs vWF available in blood, leading to bleeding tendency. vWF is required for clotting. For this reason, patients with very high platelet counts are generally not started on antiplatelet agents like aspirin, until their platelet count is brought below about 10 lac.

This patient was then treated with urgent platelet apheresis on same day Sunday, a procedure not easily available in those years, about 12 years ago. Eventually we did BMT for him in next few months, and he remains well to date in complete remission from his CML. So the points to remember:

1. Patients with very high platelet count, above about 10 lac, should be referred immediately. If they are asymptomatic, it is not urgent (unlike for high WBC). They can be seen in OPD.
2. They should not be started on an antiplatelet agent.
3. They need platelet apheresis – same procedure as making a single donor platelet – to remove excess platelet. This is a temporary reduction. Patients do need other medicines to reduce platelet production. Such as hydroxyurea, anagrelide (not easily available however), interferon alpha, and others.
4. Cut off for starting apheresis is variable. Most people would recommend this above 20 lac for sure, and many even before that. It depends on a number of factors, especially the likely cause, and clinical factors. If there is significant thrombosis, or bleeding, apheresis is more important regardless of platelet count, above 10 lac.

Que: I have heard that some patients may have platelet count above 10 lac even without blood disorder. Are they treated in same aggressive manner?

Ans: Very important point. I mentioned above “role of underlying cause” in decision making. Aggressive management is for patients with blood disorders i.e. myeloproliferative. Not for reactive causes. For example, most common reason for high platelet count is actually Iron Deficiency. Second most common cause is Infection or inflammation. Mostly these are below 10 lac. However we do see patients who have platelet above 10 lac, and sometimes even 15 lac with these conditions. They do not need any separate treatment. No hydroxyurea, apheresis, not even aspirin. Just treat underlying cause! So thank you for bringing up this point.

Just to complete discussion on high counts, very high Hb or Hct/PCV or RBC count can also lead to life threatening event. Such as Thrombosis. However this is not considered a typical oncologic emergency, as the acuity is much less. Increase in Hb is a slower process, and these patients can be managed on outpatient basis. Unless they have already developed a thrombosis, in which case they are to be treated accordingly. All high Hb patients do not have underlying myeloproliferative neoplasm. Proper diagnosis is critical, to prevent phlebotomy in patients with High Affinity Hb, or Hypoxia or smoking related high Hb. If they are symptomatic, such as with Headache, and extreme Hb e.g. around 20, early evaluation and treatment, must be done, to prevent life threatening thrombosis. If such complication can be prevented with timely treatment, otherwise their long term prognosis is good.

March 14th 2020.  Dr Chirag A. Shah; M.D. Oncology/Hematology (USA), 079 26754001. Diplomate American Board of Oncology and Hematology. Ahmedabad. drchiragashah@gmail.com