The mother of a 4-year-old boy called the nurse line because her son had what she described as an itchy, red rash on his arms and back since the night before. After a full triage, she was given instructions for symptomatic care and follow-up with the pediatrician the next day. The mother called back later that day because the patient had developed the same rash everywhere and some new bruising on his arms and legs after playing on the trampoline in the yard. She was directed to have her child evaluated in the emergency department.
The patient had not had any recent illness or travels. There were no reptiles at home, and he did not have any other unusual exposures. The child was otherwise without complaints, and was up to date on all his vaccines. Beside the skin changes, a complete review of systems was otherwise normal.
The exam was notable for normal vitals with a blood pressure of 100/59 mm Hg, heart rate of 108 bpm, respiration rate of 24 bpm, and temperature of 36.2°C. The skin findings are shown in the picture. There was no evidence of mucosal bleeding. The rest of the exam was normal.
What is the diagnosis? What is the appropriate workup, and how should the patient be treated?
Find the diagnosis and case discussion on p. 14.
Diagnosis: Immune Thrombocytopenic Purpura
Immune thrombocytopenic purpura (ITP) is one of the most common causes of symptomatic thrombocytopenia in children. The incidence is estimated to be 4.6 to 5.3 cases per 100,000 children. (Acta Paediatr 2005;94:178.) The peak years of presentation are ages 2-5, with another small spike in the adolescent years. It is a process that is usually an IgG-mediated immune response to the individual's own platelets, and the thrombocytopenia results from platelet destruction primarily by macrophages in the spleen. (Hematol Oncol Clin North Am 2013;27:495.) Generally, there is no problem with the function of the platelets that are produced; instead, IgG autoantibodies attach to the platelet membrane antigens, resulting in accelerated destruction and subsequently fewer, circulating platelets. It is referred to as primary ITP if the cause of the immune response is not known. Occasionally, an underlying disorder or infection can be identified as the likely etiology (lupus, HIV, etc.), and it is referred to as secondary ITP.
The most common presenting symptom of ITP is petechial rash (60% with isolated cutaneous bleeding). (Bussel JB. Immune thrombocytopenia [ITP] in children: clinical features and diagnosis. In: UpToDate, Mahoney DH, Waltham, MA [Accessed July 2017].) Forty percent of children will present with mucosal bleeding (nasal, gingival, etc.) and much less frequently (3%) with serious genitourinary or gastrointestinal bleeding. (Blood 2008;112:4003.) Despite many patients having platelet counts lower than 10,000, the incidence of intracranial hemorrhage (ICH) remains around 0.5 percent in this population. (Curr Opin Hematol 2007;14:515.) The majority of patients presenting with ITP had some recent viral syndrome that is thought to be the precipitant. Very rarely, recent vaccinations, specifically measles, mumps, and rubella, are thought to be the precipitant. It is not uncommon to be unable to identify what caused the patient to develop ITP.
Bone marrow biopsies, while definitive, are not routinely recommended for diagnosing ITP. Instead, careful history and physical exam in combination with peripheral blood draw results are typically sufficient for diagnosis. The recommended workup for children presenting with suspected ITP includes a complete physical exam paying special attention to neurology, skin, and the general appearance of the child. Classically, children with ITP otherwise feel well, and do not have significant changes in activity or behavior. Laboratory tests that can help with the diagnosis include a complete blood count (CBC), reticulocyte count, peripheral smear, and a Coombs test.
Patients with ITP should have a normal CBC, except for thrombocytopenia (defined as platelets of <100,000). They should also have a normal reticulocyte count and no evidence of hemolysis on the direct antiglobulin test (DAT, formerly Coombs). A peripheral smear should reveal fewer platelets but with generally normal morphology. If any of these are not true or there is clinical evidence of a more significant systemic illness, then further evaluation might be warranted to confirm the diagnosis. The differential diagnosis for patients presenting with thrombocytopenia is extensive, but some important secondary causes of ITP to keep in mind are lupus, HIV, common variable immune deficiency, and medication-induced and congenital or acquired bone marrow problems.
Treatment for ITP in children is highly variable and debated in the literature. The American Society of Hematology recommends IVIG and steroids as the first-line treatment, followed by rituximab or high-dose dexamethasone. (J Pediatr Hematol Oncol 2013;35:1.) Not surprisingly, in the published studies, approximately 72 percent of pediatric patients in the United States with ITP receive some sort of treatment. (Pediatrics 2013;131:880.) The United Kingdom has about a 16 percent rate of treatment, and the rest of the patients are managed conservatively with thrombocytopenic precautions. (Arch Dis Child 2012;97:8.)
The ultimate goal of managing patients with ITP is to prevent serious bleeding and to decrease the amount of time patient's lives are affected by thrombocytopenia. Serious bleeding remains uncommon in all pediatric patients with ITP regardless of the type of management, which makes any conclusions about definitive management elusive. The available evidence suggests that about 80 percent of patients will go into remission from their episode within a few months regardless of the treatment. (Br J Haematol 2014;165:756.) Splenectomy has been described as a highly effective treatment, but it has significant risk and potential morbidity for cases with severe bleeding or chronic cases (ITP lasting more than 12 months).
Early consultation with a pediatric hematologist is important in emergency department management. Typically, the bleeding symptoms tend to be more important than the absolute number of platelets in choosing the initial therapy. Bleeding symptoms are classified by many different scoring systems and fall into four categories: minor (isolated skin bleeding), mild (small amounts of mucosal bleeding), moderate (active mucosal bleeding not requiring transfusion), and severe (ICH or ongoing mucosal bleeding requiring transfusion). Treatment for severe bleeding is rare, but combinations of immunosuppressive therapy and platelet transfusion have all been described. (J Pediatr Hematol Oncol 2013;35:1.) Factors such as the impact on quality of life (with and without treatment), parent and patient comfort, and the best available evidence at the time should all be weighed when deciding management for patients who aren't having serious bleeding. (J Pediatr 2015;166:480.)
Our patient had an initial CBC notable for platelets of one. Other laboratory results, including the rest of his CBC, peripheral smear, and LFTs, were all normal. He received IVIG in the hospital, and was discharged on hospital day three with a platelet count of 19. He came back the following day after hitting his head on the door at home. He was watched in the ED, and subsequently discharged home without developing any symptoms or needing a CT scan. The patient has not followed up for repeat blood testing.
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