Pediatric Thrombocytosis Clinical Presentation

Updated: Oct 01, 2018
  • Author: Susumu Inoue, MD; Chief Editor: Hassan M Yaish, MD  more...
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Presentation

History

The history of patients with thrombocytosis may include the following:

  • Reactive thrombocytosis

    • The history is that of a preceding illness (eg, pneumonia, upper respiratory tract infection, urinary tract infection, iron-deficiency anemia, surgery, hemorrhage, burn, and many others) that triggers thrombocytosis. In some instances, no clear etiology is found; in these cases, investigative efforts may be necessary to exclude asymptomatic asplenia/hyposplenia, primary thrombocytosis, and hereditary thrombocytosis.

    • In general, symptoms (thrombotic or hemorrhagic) caused by a high platelet count are absent in virtually all cases of reactive thrombocytosis. However, there are exceptions as described below.

    • In a review article, Sutor reported two children with severe iron-deficiency anemia and platelet counts of more than 1 million/μL who had cerebral infarction. [32] Other comorbid factors, such as vasculitis or hereditary thrombophilia, could not be excluded. An additional four cases of stroke were reported with iron-deficiency anemia, but only one of the four had thrombocytosis. [46] Thus, it is unclear to what degree thrombocytosis contributes to these rare vascular events.

    • Though extremely rare, children with congenital nephrotic syndrome have a high frequency of thrombosis due to persistent thrombocytosis, activated states of platelets, elevated level of coagulation factors such as von Willebrand factor and factors V and VIII, and a  reduced level of antithrombotic factors such as antithrombin, protein C, and protein S. [12]

  • Essential (primary) thrombocytosis (ET)

    • The history is that of mucocutaneous bleeding, such as GI, epistaxis, or postsurgical bleeding, and excessive bruising. Though rare, children also develop hemorrhagic and/or thrombotic complications, although the frequencies are unknown. Ten of 36 children that were reviewed by Dror et al had bleeding or thrombotic episodes before the diagnosis was established. [30]

    • Headache is the most common feature in the history.

    • The patient's family members may have the same disorder. To establish familial thrombocythemia, a careful family history and platelet counts should be obtained from the suspected family members when indicated. High levels of TPO assay in multiple family members indicate TPO mutation.

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Physical

Physical findings may include the following:

  • Reactive thrombocytosis: No specific physical findings are related to the increased platelet count.

  • ET

    • Splenomegaly is common but not always present; less commonly, hepatomegaly may be present. Splenomegaly is also common in familial thrombocythemia.

    • Other physical findings may be found, depending on the hemorrhagic (typically mucous membrane bleeding) or thrombotic complications.

    • Thrombosis may affect the cerebral, coronary, and/or mesenteric arteries; the portal vein; and/or the inferior vena cava. A thrombotic event may be the presenting symptom of ET.

    • Classic erythromelalgia (throbbing, aching burning of palms and soles) associated with ET and polycythemia rubra vera has not been described in children.

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Causes

Causes are as follows:

  • Reactive (secondary) thrombocytosis

    • Infection - Meningitis, upper and lower respiratory tract infections, septic arthritis, osteomyelitis, urinary tract infection, gastroenteritis, sepsis, severe dermatitis, toxocariasis, HIV infection

    • Chronic inflammations and vasculitis - Rheumatoid arthritis, Kawasaki syndrome, Henoch-Schönlein purpura, Caffey disease, TNF (tumor necrosis factor) receptor–associated periodic (TRAP) syndrome, inflammatory bowel disease, autoimmune disease, collagen vascular disease

    • Hemorrhage, iron-deficiency anemia

    • Tissue damage - Postsurgical, burns, trauma, fracture [47]

    • Rebound thrombocytosis - cancer chemotherapy, recovery phase of immune thrombocytopenic purpura (ITP)

    • Postsplenectomy - ITP, splenectomy for hereditary spherocytosis, traumatic asplenia, post splenic artery embolization, autosplenectomy in sickle cell disease

    • Congenital asplenia, or hyposplenia associated with immunodeficiency syndrome

    • Hemolytic anemia -Sickle cell disease, thalassemia, and other hemolytic anemia

    • Renal disorders -Nephrotic syndrome, nephritis

    • Malignancy - Soft tissue sarcoma, osteosarcoma, hepatoblastoma, hepatocellular carcinoma, malignant ovarian tumor [48]

    • Low birth weight/preterm infants

    • Miscellaneous causes - Use of low molecular–weight heparin, granulocyte-colony stimulating factor treatment in neonates, familial urticaria pigmentosa

    • PACAP deficiency

  • Primary or essential thrombocytosis

    • Myelofibrosis with myeloid metaplasia

    • Polycythemia vera - PRV-1 overexpression may be present.

    • Chronic myelocytic leukemia: BCR-ABL fusion gene is present.

    • Familial essential thrombocytosis - MPL or TPO gene mutation may be present; blood TPO assay may be helpful (high); this includes K39N substitution of MPL gene, MPLBaltimore (polymorphism is limited to African American population)

    • Essential thrombocytosis - JAK2V617Fmutation or CALR gene mutation may be present; the frequency of JAK2V617F is lower in children (11-50%) than in adults (>50%); frequency of CALR mutation in children is not known; JAK2V617I mutation somatic cells described in one family; MPL gene mutations

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