Polymorphic eruption of pregnancy
PEP occurs in about 0.5% of pregnancies and is associated with a higher frequency of multiple gestation and significant intrapartum weight gain (with a higher degree of stretching of abdominal skin). Other risk factors include primiparity and Northern European descent. It is important to note that there is no association with adverse fetal or maternal outcomes. PEP is self-limiting and typically resolves within 4 weeks of rash onset, usually 2 weeks postpartum. Recurrence with subsequent pregnancies is uncommon.
O26.86 – Pruritic urticarial papules and plaques of pregnancy (PUPPP)
88697005 – Pruritic urticarial papules and plaques of pregnancy
Differential Diagnosis & Pitfalls
- Impetigo herpetiformis has distinct pustules.
- Pemphigoid (herpes) gestationis is an autoimmune blistering disease that occurs in pregnancy. Vesicles and bullae are diagnostic hallmarks but may be absent early on. A positive direct immunofluoresence (DIF) can help to differentiate early cases of pemphigoid gestationis from PEP.
- Intrahepatic cholestasis of pregnancy also presents with intense itching. There are no primary lesions, but secondary lesions such as excoriations and pruriginous lesions may be seen. Itching starts on the palms and soles, rather than spares them, as in PEP. Bile acids and liver function tests may be ordered to further differentiate, if needed.
- The target lesions of PEP may be confused with erythema multiforme. Differentiate with history, clinical presentation, and histology.
- Exanthematous drug eruption
- Atopic eruption of pregnancy
- Insect bites
- Contact dermatitis (irritant, allergic)
- Seabather's eruption
- Viral syndromes may also present with red papules similar to PEP. See viral exanthem.