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A boy in middle childhood presented with widespread petechiae and a vesicular purpuric rash distributed all over the body but predominantly affecting the lower limbs (figure 1). It was preceded by 7 days of a painless pruritic progressive maculopapular erythematous rash. He had no mucosal involvement and was otherwise well and afebrile throughout. He had a severe thrombocytopenia (platelets 7×109/L), mild neutropenia, normal coagulation profile and reactive lymphocytes on blood film. Varicella zoster virus (VZV) PCR from vesicular fluid was positive. He was given oral acyclovir and discharged with precautionary advice; no additional treatments were required. He made a good recovery with no bleeding episodes, healing of vesicles and gradual improvement in platelet count (43×109/L at week 3).
This child had immune thrombocytopenic purpura (ITP) secondary to VZV. ITP is the most common acquired bleeding disorder in children, and it occurs due to immune-mediated platelet destruction by autoantibodies and reduced platelet production.1–3 Compared with adults, ITP in children is more often benign and self-limiting.4 In almost two-thirds of children, there is a history of viral infection prior to the diagnosis.4 Specific viral triggers are rarely identified, with the exception of varicella zoster which can be recognised clinically and supported by PCR testing.4–6 Other secondary causes include bacterial infections, malignancy and autoimmune disease.1–3 ITP has also been reported in response to VZV vaccinations.1–3
In this case, haemorrhagic varicella was a key differential. In haemorrhagic varicella, children present systemically unwell, often with a history of immunosuppression, findings of leucocytosis, thrombocytopenia, transaminitis and potential signs of disseminated intravascular coagulation (DIC).6 7 Another differential was Henoch-Schonlein purpura. However, the widespread and circumferential lower limb distribution and vesicular quality went against this diagnosis.1 Clinicians should be aware that ITP remains a diagnosis of exclusion.1 2
In over 75% of children, platelet count resolves spontaneously, and treatment is guided by bleeding symptoms.8–10 Children with no bleeding, or only mild bleeding, can be managed with observation alone even with platelets <10×109/L.8 10 This is based on the extremely low likelihood of children developing significant bleeding.8 First-line treatments are similar for children and adults and may include corticosteroids or intravenous immunoglobulin (IVIG).8–10 When steroids are indicated, shorter courses of high-dose steroids are effective without the risk of serious or long-term side effects.8–10 While steroids are effective in increasing platelet counts, they may precipitate visceral disseminated or haemorrhagic varicella.5 11 For children requiring treatment, and in whom corticosteroids are contraindicated, guidelines suggest the use of IVIG.8 Treatment can lead to a faster recovery and less severe bleeding events.9 12 However, there is no evidence that this is clinically significant in children without active bleeding.9 10 12Additional treatments including antirhesus immunoglobulins (anti-D), while thrombopoietin receptor agonists, rituximab and splenectomy are considered in refractory cases.8 10
Varicella zoster is a rare viral trigger for immune thrombocytopenic purpura.
Children without bleeding symptoms can be observed.
The potential for steroids to precipitate disseminated varicella should be considered.
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Contributors The following authors were responsible for drafting of the text, sourcing and editing of clinical images, investigation results, drawing original diagrams and algorithms, and critical revision for important intellectual content: CH, OH and MB. The following authors gave final approval of the manuscript: CH, OH and MB.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Case reports provide a valuable learning resource for the scientific community and can indicate areas of interest for future research. They should not be used in isolation to guide treatment choices or public health policy.
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.