A 6-year-old girl was brought to the emergency department (ED) by her mother after the child bumped her head while playing. While the physician examined the child’s head, the mother remarked that her daughter had recently developed bruises that appeared suddenly and only after minor, if any, known trauma. The ED physician determined that the child’s bump to the head was nothing to worry about, attributed the bruising to the child being a “healthy, active 6-year-old,” and sent her home.
Two days later, the child was brought to our office because the mother was still concerned about her daughter’s easy bruising. The mother pointed out ecchymosis scattered across her daughter’s extremities and torso. The child denied any pain or other complaints, including any active or recurrent bleeding. Upon further questioning, the mother mentioned that her daughter had recovered from a coldlike illness several weeks earlier.
We ordered a complete blood count (CBC) and peripheral smear, which were normal except for the platelet count, which was 7,000/μL (normal, 150,000-450,000/μL). Based on the child’s easy bruising and isolated thrombocytopenia, we diagnosed immune thrombocytopenia, which is also known as idiopathic thrombocytopenic purpura (ITP).
In ITP, autoantibodies are directed against platelets, leading to their sequestration and destruction in the spleen and a resultant drop in platelet count.1 Children with ITP typically present between the ages of 2 and 10, with a peak incidence between 2 and 5.2 The incidence is estimated to be as high as 8 per 100,000 children.3 However, this estimate primarily reflects symptomatic children, and the true incidence of childhood ITP may be much higher because asymptomatic children may not be brought in to see a doctor.
For the majority of patients, ITP resolves within three months. However, for 20% to 30% of patients, thrombocytopenia will last beyond six months, with or without treatment.4 In 1% of cases, patients will have a recurrence of ITP.3
In addition to easy bruising, nearly all patients who present with possible ITP will complain of cutaneous bleeding, typically a nose bleed or bleeding in the oral cavity.2 Upon questioning, 60% of patients will report a history of recent infection.4 Not surprisingly, bleeding severity correlates inversely with platelet count; severe bleeding is seen in patients with a platelet count < 10,000/μL.
While rare, the more worrisome complications include intracranial hemorrhage (incidence, 0.1% to 0.8%) and other serious hemorrhages that would require transfusion (estimated incidence, 2.9%).2
Vast differential seen in child bruising
When a child presents with bruising, perform a thorough history, including birth and prenatal course, as well as a physical to exclude other potential causes, such as physical abuse, use of herbal remedies or other natural supplements that may not be disclosed as medication, or even environmental exposure. When bruising is present in a child who has isolated thrombocytopenia, the diagnosis of ITP may be straightforward. However, many conditions share thrombocytopenia in their disease process and should be considered in the differential diagnosis of a child who you suspect may have ITP.
• Suspect physical abuse in a bruised child who does not have thrombocytopenia, whose mood is flat or depressed, or who has experienced recurrent injuries or bruising.
• Leukemia, particularly acute lymphoblastic leukemia (ALL), the predominant leukemia found in children, should be ruled out as well. Symptoms that may distinguish a child with ALL from one with ITP include fever, weight loss, and joint pain, as well as signs such as lymphadenopathy, hepatosplenomegaly, anemia, and leukocytosis. A peripheral smear may be ordered to help confirm or exclude a diagnosis of ALL, should any of the above be present in a child with thrombocytopenia.5 It may show lymphoblasts and/or atypical cells in a patient with ALL.5
• Infections should also be included in a differential when a patient is suspected of having ITP, particularly if he or she has systemic symptoms. Viral infections that may cause thrombocytopenia include mononucleosis, dengue virus, human herpesvirus-6, and HIV.6,7
ITP often follows an infection, and the incidence of ITP may be higher during winter months, when infections are more common. However, infection may not always be the cause of ITP. Sepsis may also lead to thrombocytopenia, but a child with sepsis would present very differently from one who has only ITP. A septic child would present with acute illness and signs and symptoms of severe systemic illness, such as high fever, altered mental status, tachycardia, pallor, diaphoresis, and hypotension.
• Drug-induced thrombocytopenia (DIT) should be considered in any child who is taking or recently took a medication that may cause thrombocytopenia. Medications that can cause thrombocytopenia include heparin, quinine, vancomycin, trimethoprim-sulfamethoxazole, rifampin, carbamazepine, phenytoin, piperacillin, linezolid, and valproic acid.8 The measles, mumps, and rubella vaccine also can cause thrombocytopenia.8 A careful medication history may determine if the child is at risk for DIT.
• To narrow the differential, obtain a CBC and peripheral smear when evaluating a patient you suspect may have ITP5 (strength of recommendation [SOR]: A). A CBC will determine the patient’s platelet count, and a peripheral smear should be obtained to exclude other possible diagnoses.5
If there are any questions regarding the results of a peripheral smear, it may be necessary to perform a bone marrow aspiration. This, however, is not usually necessary in an otherwise typical case of ITP.9 Bone marrow aspiration may, however, be necessary to reevaluate the initial diagnosis for a child who does not respond to treatment for ITP.
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