Polymorphic eruption of pregnancy: clinicopathology and potential trigger factors in 181 patients

Summary Background Polymorphic eruption of pregnancy (PEP; synonym: pruritic urticarial papules and plaques of pregnancy) is the most common specific dermatosis of pregnancy. However, its clinical characterization is controversial and its pathogenesis uncertain. Objectives To evaluate clinical characteristics of and potential trigger factors for PEP in a large mixed ethnic population. Methods A retrospective analysis of epidemiological, clinical, immunopathological and obstetric findings in 181 patients with PEP seen at two university‐based dermatological hospitals in Graz, Austria, and London, U.K. Results PEP mainly affected white (88%) primigravidae (70%) in late pregnancy (83%; mean ± SD onset 34 ± 5 weeks) or the immediate postpartum period (15%). The most commonly involved sites were the abdomen and proximal thighs (97%). Involvement of the whole skin, including the face, palms and soles, was only rarely observed. While pruritic urticarial papules and plaques were the main morphological features at disease onset (98%), more than one‐half of the patients (51%) later developed polymorphous features including erythema, vesicles, and targetoid and eczematous lesions. Topical treatment with corticosteroids and emollients was sufficient to control symptoms in the majority of patients, and skin lesions resolved after a mean ± SD of 4 ± 3 weeks. Multiple gestation pregnancies were observed in 13% of cases, excessive maternal weight gain in 78%. Conclusions Our data confirm the benign, self‐limiting nature of PEP and its favourable outcome for both the mother and the fetus. For the first time, we have documented a characteristic change in morphology with disease progression. The evidence of polymorphous clinical features in more than one‐half of the patients favours the use of the term PEP. Multiple gestation pregnancies and excessive maternal weight gain, but not fetal weight and sex, were found to be significantly associated with PEP.