A 6-week-old male infant presented to urgent care with fever, congestion, and a rash of diffuse erythematous papules and patches on his palms and soles. He was treated with a 10-day course of cephalexin. The rash began peeling, and his symptoms improved. After 1 month, the rash recurred (Figure 1 and Figure 2). The infant had been born at term to a 20-year-old gravida 1, para 1 mother. The pregnancy was complicated by obesity, chronic hypertension, Trichomonas infections in the first trimester, and chlamydia at delivery.

QUESTION

Based on the patient’s history and physical examination, which one of the following is the most likely diagnosis?

• A. Congenital syphilis.

• B. Coxsackievirus infection.

• C. Impetigo neonatorum.

• D. Viral exanthem.

DISCUSSION

The correct answer is A: congenital syphilis, which results from the spread of Treponema pallidum through the placenta or by contact with an untreated mother’s lesions during delivery. In affected infants, rhinitis can present during the first week of life due to mucous membrane involvement. The rash typically develops 1 to 3 weeks later as papulosquamous or red, pink, or copper-colored maculopapular lesions on the back, buttocks, posterior thighs, palms, and soles. Eventually, the rash desquamates and crusts. The presentation varies, and syphilis should be suspected in patients who are at risk. Treatment consists of 10 days of intravenous penicillin G.¹