A 5-year-old boy presents with a rash behind the ear that has spread to the face and chest, with cold extremities and lethargy. Which infection is most likely?

A 5-year-old boy presents with a rash behind the ear that has spread to the face and chest, with cold extremities and lethargy. Which infection is most likely?

• A. Measles
• B. Varicella
• C. Rubella
• D. Roseola

Answer: (C)

Recognizing patterns of pediatric exanthems and their accompanying signs helps distinguish rubella from other viral infections. The rash described—beginning behind the ear and spreading to the face and trunk—fits rubella, which typically presents with a mild fever and a maculopapular rash that starts on the face (often around the ears or scalp) and moves downward. A classic clue is posterior auricular or occipital lymphadenopathy, which is common with rubella. The illness is usually mild, so symptoms like cold extremities and lethargy can occur but aren’t dominant features. In contrast, measles usually has a higher fever with prominent prodromal symptoms (cough, coryza, conjunctivitis) and Koplik spots; varicella shows vesicular lesions in various stages, often pruritic and more trunk-centric; roseola typically affects younger children with a high fever that resolves before a trunk-predominant rash appears. The combination of facial-origin rash and typical lymph node involvement makes rubella the most likely infection here.

Recognizing patterns of pediatric exanthems and their accompanying signs helps distinguish rubella from other viral infections. The rash described—beginning behind the ear and spreading to the face and trunk—fits rubella, which typically presents with a mild fever and a maculopapular rash that starts on the face (often around the ears or scalp) and moves downward. A classic clue is posterior auricular or occipital lymphadenopathy, which is common with rubella. The illness is usually mild, so symptoms like cold extremities and lethargy can occur but aren’t dominant features.

In contrast, measles usually has a higher fever with prominent prodromal symptoms (cough, coryza, conjunctivitis) and Koplik spots; varicella shows vesicular lesions in various stages, often pruritic and more trunk-centric; roseola typically affects younger children with a high fever that resolves before a trunk-predominant rash appears. The combination of facial-origin rash and typical lymph node involvement makes rubella the most likely infection here.