A 3-year-old boy is brought to the clinic by his parents for fever and rash. Two days ago, the patient developed fever and decreased appetite. Yesterday, a maculopapular rash appeared on his trunk and face and became vesicular. This morning, another small group of vesicles appeared on his arms and legs. The rash is intensely pruritic. The child is playful and has been drinking normally. He is up to date on immunizations and has no medical issues. The patient attends day care. The family travels extensively for the mother's job, and they recently returned from a 2-week trip to South Africa. Temperature is 38.2 C (100.8 F), and pulse is 100/min. Physical examination shows a mild, diffuse maculopapular rash with some scattered vesicular lesions. The mucous membranes are normal. Which of the following is the most likely explanation for this rash?

Question

A 3-year-old boy is brought to the clinic by his parents for fever and rash.  Two days ago, the patient developed fever and decreased appetite.  Yesterday, a maculopapular rash appeared on his trunk and face and became vesicular.  This morning, another small group of vesicles appeared on his arms and legs.  The rash is intensely pruritic.  The child is playful and has been drinking normally.  He is up to date on immunizations and has no medical issues.  The patient attends day care.  The family travels extensively for the mother's job, and they recently returned from a 2-week trip to South Africa.  Temperature is 38.2 C (100.8 F), and pulse is 100/min.  Physical examination shows a mild, diffuse maculopapular rash with some scattered vesicular lesions.  The mucous membranes are normal.  Which of the following is the most likely explanation for this rash?

Quizplus · Accepted Answer

11ec25c8_d6b8_e16b_bc81_cd5c4926e3bc_MD0003_00 This child has a mild case of varicella (chickenpox), which is caused by the highly infectious varicella-zoster virus (VZV). Approximately 2 weeks after exposure to airborne particles, patients with varicella develop a brief prodrome (eg, fever, malaise) followed by onset of rash within 24 hours. The rash is initially maculopapular but rapidly becomes intensely pruritic and vesicular involving the trunk, face, and extremities. The vesicles can become pustular and subsequently crust over. Successive "crops" of vesicles appear daily over a week, resulting in vesicles at different stages. vesicular Varicella is generally a self-limiting infection that does not require antiviral therapy. In rare cases, varicella can cause cerebellar ataxia or pneumonia. Superimposed aggressive group A streptococcal infection can also develop and should be treated with antibacterial therapy. The incidence of varicella in the United States has declined significantly due to universal vaccination. However, breakthrough infection is possible and occurs most frequently in children who have received only a single dose of VZV vaccine, as in this 3-year-old patient (who is up to date on immunizations but would not have received the second dose of VZV, given at age 4). Breakthrough varicella is generally mild with lower fever and fewer vesicles. (Choice A) Eczema herpeticum is caused by herpes virus infection of areas of skin affected by atopic dermatitis, leading to painful vesicular rash, fever, and possibly viral dissemination. This child does not have a history of atopic dermatitis. vesicular rash (Choice B) Hand-foot-and-mouth disease is caused by enteroviruses (most commonly coxsackievirus). It presents with an exanthem of lesions on the hands and feet (including the palms and soles) that may be vesicular but are rarely painful or pruritic as well as an oral enanthem of macules or ulcers in the mouth (causing mouth pain). This child has an exanthem but no enanthem. hands feet (Choice C) Impetigo is caused by bacterial infection of the skin, usually due to Staphylococcus aureus or Streptococcus pyogenes. Painful, erythematous lesions progress to "honey-crusted" ulcerations or plaques, which are not seen in varicella. lesions (Choices D and F) Both measles and rubella infection are maculopapular rashes that begin on the face and spread cephalocaudally. Vesicular lesions are not seen in either measles or rubella. maculopapular (Choice E) Roseola is caused by human herpesviruses 6 and 7. Patients have high fever followed by a diffuse maculopapular rash that appears as the fever abates. Roseola does not cause vesicles. (Choice G) Scabies is a highly contagious infection caused by the Sarcoptes scabiei mite. Scabies classically presents as an extremely pruritic, erythematous, papular rash in the interdigital web spaces, flexor surfaces of the wrist, extensor surfaces of the elbows, and periumbilical area. interdigital web spaces Educational objective: Varicella (chickenpox) is characterized by successive crops of intensely pruritic vesicles. The disease is usually self-limiting and has been significantly reduced in the United States by widespread immunization with a 2-dose series. References: Two-dose varicella vaccine effectiveness and rash severity in outbreaks of varicella among public school students. (http://www.ncbi.nlm.nih.gov/pubmed/24911894)

A 3-Year-Old Boy Is Brought to the Clinic by His