A 4-year-old girl is brought to the office for evaluation of a rash that developed yesterday and is mildly pruritic. The patient received the measles-mumps-rubella vaccine in her left thigh and varicella-zoster virus vaccine in her right thigh 2 weeks ago. The patient has mild persistent asthma and uses inhaled steroids daily and bronchodilators as needed. She also has a history of peanut anaphylaxis and she carries an epinephrine pen. The patient has no known sick contacts. Her 6-year-old brother is undergoing chemotherapy for acute lymphoblastic leukemia. Temperature is 37.8 C (100 F). Examination shows 6 scattered papular and vesicular lesions on her chest. Auscultation of the chest reveals clear breath sounds and no wheezes or crackles. Which of the following is the most likely mechanism of this patient's presentation?

Question

A 4-year-old girl is brought to the office for evaluation of a rash that developed yesterday and is mildly pruritic.  The patient received the measles-mumps-rubella vaccine in her left thigh and varicella-zoster virus vaccine in her right thigh 2 weeks ago.  The patient has mild persistent asthma and uses inhaled steroids daily and bronchodilators as needed.  She also has a history of peanut anaphylaxis and she carries an epinephrine pen.  The patient has no known sick contacts.  Her 6-year-old brother is undergoing chemotherapy for acute lymphoblastic leukemia.  Temperature is 37.8 C (100 F).  Examination shows 6 scattered papular and vesicular lesions on her chest.  Auscultation of the chest reveals clear breath sounds and no wheezes or crackles.  Which of the following is the most likely mechanism of this patient's presentation?

Quizplus · Accepted Answer

Explanation: 11ec25c8_d6bb_5271_bc81_8964dd77fe38_MD0003_00 This child has developed a pruritic, vesicular rash approximately 2 weeks after receiving the live-attenuated varicella-zoster virus (VZV) vaccine. The two potential causes of varicella-like rashes after VZV vaccine include: Attenuated vaccine virus can replicate after immunization and cause mild infection in approximately 3% of immunized children. Wild-type VZV can cause classic varicella if acquired before the child's immunization results in protective antibody Both vaccine-strain and wild-type varicella have an incubation period of 1-3 weeks. In this case, the child's mild rash and lack of fever suggest that her symptoms are caused by the attenuated vaccine virus. The lesions of the vaccine-strain virus are generally few in number (<10) and are more likely to be maculopapular rather than entirely vesicular. In contrast, classic varicella disease presents with >100 vesicular lesions in successive "crops" over several days. vesicular lesions The disease caused by vaccine-strain virus is very mild and is not a contraindication to future VZV vaccine administration. The vaccine-strain virus is less contagious than wild-type varicella, but it can be transmitted to other individuals. Therefore, patients who develop a rash after receiving the VZV vaccine should avoid contact with high-risk individuals who are susceptible to varicella (eg, pregnant women, people receiving chemotherapy) until the rash has completely crusted over. (Choice A) Autoantibodies against platelet membrane antigens cause immune thrombocytopenic purpura. This child does not have the characteristic petechial rash of this condition. (Choices B and C) Allergic reactions to VZV vaccine can be due to either T cell-mediated (type 4) or IgE-mediated (type 1) reactions against vaccine components, most commonly neomycin or gelatin. Type 1 reactions appear immediately after immunization, with symptoms ranging from acute hives to anaphylactic shock. Type 4 reactions occur within 2-3 days and can present with redness and swelling at the injection site. (Choice D) Primary measles infection presents with fever and a maculopapular rash that spreads cephalocaudally, neither of which is present in this patient. rash Educational objective: The varicella-zoster virus vaccine is recommended for all children at ages 1 and 4 to prevent primary varicella infection. The live-attenuated vaccine virus can cause a varicella-like rash that is mild but contagious. References: Varicella vaccines. (http://www.ncbi.nlm.nih.gov/pubmed/22123665)

A 4-Year-Old Girl Is Brought to the Office for Evaluation