Differential Diagnosis for a 4-year-old with a Viral Infection
Single most likely diagnosis
- Parvovirus B19 (Fifth Disease): Characterized by a "slapped-cheek" appearance due to the rash on the face, which can be accompanied by a mild fever and upper respiratory symptoms. The rash typically fades within 5 days, fitting the described timeline.
Other Likely diagnoses
- Roseola: Caused by human herpesvirus 6 (HHV-6) or human herpesvirus 7 (HHV-7), it presents with high fever followed by a rash that appears as the fever resolves. While the rash can appear anywhere, it often spares the face or is less prominent there, but it's not uncommon for it to be present.
- Enterovirus Infection: Enteroviruses can cause a variety of symptoms including fever, rash, and upper respiratory symptoms. The rash can be localized or widespread and may include the face.
Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Kawasaki Disease: Although less common, Kawasaki disease is a critical diagnosis to consider due to its potential for causing coronary artery aneurysms. It presents with fever, rash, conjunctivitis, cervical lymphadenopathy, and changes to the lips and oral cavity. The rash can vary in appearance and may include the face.
- Meningococcemia: This is a severe infection caused by Neisseria meningitidis, which can present with a rash, fever, and signs of meningitis or sepsis. The rash can start as small, pink spots that quickly turn into purple spots or blood blisters, and while it can appear anywhere, it may initially be noted on the face or extremities.
Rare diagnoses
- Scarlet Fever: Caused by Group A beta-hemolytic streptococci, it presents with a distinctive rash that feels like sandpaper, a red, lacy appearance, and strawberry tongue. The rash typically starts on the chest and spreads, but it can involve the face.
- Measles: Characterized by a morbilliform rash that starts on the face and descends, accompanied by fever, cough, runny nose, and conjunctivitis. Although vaccination has made measles less common, it remains a consideration in areas with low vaccination rates or during outbreaks.