Pediatric infectious rashes: Clinical

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Pediatric infectious rashes: Clinical

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An 11-month-old girl was brought to the emergency department by her parents for the evaluation of high fever and a rash. The rash first appeared on her face last night and has now spread over her entire body. Prior to the onset of the rash, the patient had intermittent cough and runny nose. She did not receive any vaccinations since birth due to parental preference. The rest of the history is noncontributory. Temperature is 38.8°C (102°F), pulse is 98/min, respirations are 27/min and blood pressure is 90/55 mmHg. Physical examination shows an irritable and restless child with a diffuse erythematous maculopapular rash all over the body sparing the palms and soles bilaterally. Oral examination shows tiny, white round lesions on the buccal mucosa. Administration of which of the following is associated with decreased morbidity and mortality in this patient? 


When approaching a child with a rash, the first step is to put it into one of four categories - maculopapular, vesicular, petechial or purpuric, and desquamating rashes.

A maculopapular rash has macules, which are up to 5 mm in diameter, and completely flat, meaning that you can’t feel them if you run your finger over them. It also has papules, which are raised bumps that are up to 1 cm in diameter.

A vesicular rash has vesicles, which are up to 5 mm in diameter, and look like clear blisters filled with fluid.

A petechial rash and a purpuric rashes, both have flat, red-brown spots that represent bleeding into the skin. These spots do not blanch or turn white when they get pressed. If the spots are smaller than 2 mm in diameter it’s a petechial rash, and if the spots are larger than 2 mm it’s a purpuric rash.

Finally, there are desquamating rashes, which cause peeling of the skin, like after a sunburn.

Let’s start with maculopapular rashes. First up is erythema infectiosum, or fifth disease, which is caused by parvovirus B19. The virus causes flu-like symptoms along with a fever, that lasts a few days.

Typically, just as the symptoms start to improve, a rash breaks out on both cheeks, often called "slapped‑cheeks” rash. There can also be a maculopapular, lacy rash on the body, that becomes more prominent after sun or heat exposure.

Most of the time, everything resolves in a week, but sometimes there can be complications like anemia due to reduced production of reticulocytes that lasts for a few weeks.

This can be dangerous in children with chronic hemolytic diseases, like sickle cell disease who rely on a high reticulocyte count and can have an aplastic crisis. So in these situations, packed red blood cell transfusions may be needed.

In addition, if a pregnant female gets parvovirus B19, she can transmitted the infection to her fetus. The virus can get into the fetal bone marrow, and can cause anemia, which is called "hydrops fetalis” and is usually fatal, resulting in spontaneous abortion.


Pediatric infectious rashes are a common symptom of various infectious diseases in children. In children. infectious rashes can be divided into four main types. These are maculopapular rashes, vesicular, petechial or purpuric, and desquamating rashes.

Maculopapular rashes are seen in conditions like erythema infectiosum or fifth disease caused by parvovirus B19. Maculopapular rashes are also seen in measles, rubella, and roseola. The virus causes flu-like symptoms along with a fever that lasts a few days. Next, vesicular rashes, which are characterized by vesicles covering the body, are seen in chickenpox, shingles, and in hand-foot-mouth disease.

Petechial or purpuric rashes are seen in a septic child and may signify meningococcemia, whereas, purpura on the lower limbs and buttocks in a well-appearing child plus arthritis, abdominal pain, and glomerulonephritis, may be underlying signs of Henoch Schonlein Purpura. Last but not least, desquamating rashes are seen in Scarlet fever and Kawasaki disease.


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