A 22-year-old pregnant woman at 34 weeks of gestation presented with an itchy rash that had appeared several days earlier. The rash began on her lower abdomen and slowly spread to her thigh skinfolds, armpits, breasts, back, upper arms, and legs.
The patient was otherwise healthy and was having an uneventful pregnancy. Her only recent medications were prenatal vitamins and diphenhydramine (Benadryl). She denied using new laundry detergent, deodorant, or soap. She also denied having any fever, chills, or other constitutional symptoms.
On examination, she was in no apparent distress and had normal vital signs. Her sclera were anicteric. Her skin showed numerous symmetric, confluent, erythematous, urticarial plaques and papules distributed over her axillae, abdomen, upper legs, breasts, and back, sparing her labia and face (see accompanying figure). There was no crust, scale, or discharge from the rash.
The correct answer is E: pruritic urticarial papules and plaques of pregnancy (PUPPP). PUPPP, also known as polymorphic eruption of pregnancy, is a common gestational skin condition affecting one in 160 pregnancies. It is characterized by pruritic, urticarial papules that suddenly appear late in the third trimester, usually on abdominal striae. The lesions then may spread symmetrically over the next few days to include the buttocks, proximal arms, and thighs, where they often coalesce into plaques. The morphology of the lesions may vary from erythematous, edematous papules and plaques to vesicles or target-like lesions.1
Treatment of PUPPP is supportive and includes symptomatic relief of pruritus, including oral antihistamines, topical antipruritic agents, and, in severe cases, systemic corticosteroids. Patients should be educated that the condition is self-limited and no adverse consequences to the fetus have been noted. The mean duration of the eruption is six weeks, but the rash usually is not severely pruritic for more than one week. Symptoms typically resolve within one week of delivery, and recurrences in future pregnancies are uncommon.1
Pemphigoid gestationis (herpes gestationis) is a rare noninfectious gestational dermatosis affecting fewer than one in 50,000 pregnancies. It presents as intensely pruritic, erythematous plaques that coalesce to form large polycyclic rings, which later evolve into tense blisters. The bullae rupture, leaving denuded areas that slowly heal without scarring.1
Erythema multiforme is a hypersensitivity eruption characterized by round, erythematous macules that evolve into target-shaped plaques in a symmetric distribution. The early lesions may be asymptomatic, pruritic, or painful. Episodes are preceded most often by a herpes simplex infection, upper respiratory tract infection, or atypical pneumonia.1 This patient did not have the characteristic target-like lesions, and her rash was more intensely pruritic than a typical erythema multiforme eruption.
Drug eruptions can mimic many dermatoses, including urticarial reactions. Usually they appear symmetrically on the trunk, thighs, upper arms, and face, although the face often is spared. The most common drug eruptions are maculopapular, and they often are pruritic. Diagnosis is made most often from a careful medication history. Drug eruptions typically occur seven to 10 days after starting the medication, but they sometimes do not appear until after the drug is stopped.1 This patient had not taken any new medications recently and had started diphenhydramine after her rash began.
Intrahepatic cholestasis of pregnancy is a condition characterized by generalized pruritus caused by deposition of bile acids in the skin. There are no primary skin lesions associated with this condition, although secondary excoriations may be present. Jaundice and hyper-bilirubinemia also may be present.2 This diagnosis is not consistent with this patient because she had pruritic erythematous papules and plaques with no evidence of jaundice.
|Pemphigoid gestationis (herpes gestationis)||Pruritic, erythematous plaques and polycyclic rings that evolve into blisters|
|Erythema multiforme||Round, erythematous macules that evolve into target-shaped plaques|
|Drug eruption||Most often symmetric, maculopapular, and pruritic|
|Intrahepatic cholestasis of pregnancy||Jaundice and generalized pruritus|
|Pruritic urticarial papules and plaques of pregnancy||Pruritic urticarial papules and plaques that usually begin on abdominal striae late in the third trimester|