How would you diagnose this woman’s lesions?

This 37-year-old woman presented at week 29 of her third pregnancy with a slightly pruritic rash on her trunk and proximal extremities of 1 week’s duration. Her pregnancy had been uneventful. She denied any new exposures, recent illnesses, or new medications. The lesions appeared slightly erythematous and were oval shaped with minimal scale.

How would you diagnose this woman’s lesions?

A. Nummular eczema
B. Tinea corporis
C. Pityriasis rosea
D. Secondary syphilis
E. Pruritic urticarial papules and plaques of pregnancy (PUPPP)

Bonus question: What counseling, if any, would you provide about her pregnancy because of this rash?

Answer on next page

Answer: Pityriasis rosea

This patient has pityriasis rosea. This condition typically is seen after an upper respiratory tract infection, and while the patient denied any recent illnesses, she most likely was exposed to a precipitating pathogen. Fortunately, no warnings are necessary in pregnancy with this condition.

Nummular eczema typically would not be this widespread on the trunk, and usually is much itchier. Tinea corporis rarely is this extensive and is more pruritic and more scaly. Secondary syphilis always is a consideration, especially when the palms and soles are involved, which is not the case here. PUPPP typically is seen with a first pregnancy, tends to start and be concentrated on the abdomen, and typically is very pruritic.