Dermatology MCQ - Viral Infections - Rubella

A 5-year-old child presents with a low-grade fever, pinkish maculopapular rash that started on the face and spread to the trunk and extremities, and posterior cervical lymphadenopathy. The child’s mother is in the first trimester of pregnancy. Which of the following is the most significant complication if the mother becomes infected?

A) Congenital rubella syndrome
B)) Erythema infectiosum
C) Kawasaki disease
D) Scarlet fever
E) Roseola infantum

Correct Answer: A) Congenital rubella syndrome

Explanation

This presentation is classic for rubella (German measles), a viral exanthem caused by the rubella virus.

Key Clinical Features of Rubella:

• Prodrome: Low-grade fever, malaise, upper respiratory symptoms (often mild in children).

• Rash: Pinkish-red maculopapular rash that begins on the face and spreads cephalocaudally to the trunk and extremities. The rash typically fades in 3 days without desquamation.

• Lymphadenopathy: Posterior cervical, postauricular, and occipital lymphadenopathy is characteristic and may precede the rash.

• Other Features: Arthralgia (more common in adults), conjunctivitis.

Complication in Pregnancy:

• Congenital Rubella Syndrome (CRS): If a pregnant woman (especially in the first trimester) is infected, the virus can cross the placenta and cause severe fetal defects:

  • Classic Triad:

    1. Cataracts

    2. Sensorineural deafness

    3. Congenital heart disease (e.g., patent ductus arteriosus, pulmonary stenosis)

  • Other Manifestations: Microcephaly, intellectual disability, hepatosplenomegaly, "blueberry muffin" rash (dermal erythropoiesis).

• Risk: Highest in the first trimester (up to 85% risk of CRS if infected before 12 weeks gestation).

Why Not the Other Options?

• (B) Erythema infectiosum: Caused by parvovirus B19, presents with "slapped cheek" rash and lace-like rash on extremities. Maternal infection can cause fetal hydrops, not CRS.

• (C) Kawasaki disease: Causes fever, conjunctivitis, rash, and cervical lymphadenopathy but also has lip/oral changes, extremity changes, and coronary artery aneurysms.

• (D) Scarlet fever: Caused by group A Streptococcus, presents with sandpaper rash, strawberry tongue, and desquamation during recovery.

• (E) Roseola infantum: Caused by HHV-6, presents with high fever followed by rash after fever resolves.

Management:

• Diagnosis: Serology (rubella-specific IgM) or PCR.

• Treatment: Supportive care; no specific antiviral.

• Prevention: MMR vaccine (live attenuated) is highly effective. Vaccination of women of childbearing age is critical to prevent CRS.

Prognosis:
Excellent in children; self-limiting. CRS has lifelong consequences for affected infants.

Note: Rubella is a vaccine-preventable disease. The description of the rash spreading from face to trunk + posterior cervical lymphadenopathy is highly suggestive. Always consider rubella in unvaccinated individuals and pregnant contacts.