History
A 31-year-old woman presents during the 35th week of her first pregnancy. She is very anxious about the development of extremely itchy ‘lines’ over her abdomen over the last two days. She is otherwise well with an unremarkable antenatal history to date. Her dates are confirmed on ultrasound scanning. She has no previous history of skin problems.
Examination
She has striking erythematous, linear, urticated lesions in a concentric and, in some areas, coalescing distribution over her pregnancy-distended abdomen (Fig. 32.1). The eruption corresponds with the striae distensae and there is sparing of the umbilicus. She has a few similar lesions over her upper thighs. She is normotensive and the remainder of her examination is normal. It is of note that according to her antenatal notes she has gained 5 kg since her last antenatal check 3 weeks ago. Urine dipstick is negative.
Questions
• What is this eruption?
• What other diagnoses would you consider?
• What are the implications for the baby?
Medicine
This presentation with a very pruritic eruption beginning in the third trimester of the first pregnancy and arising within the striae distensae (sparing the umbilicus) is typi-cal of pruritic urticarial papules and plaques of pregnancy (PUPPP), also referred to as toxic erythema of pregnancy or polymorphic eruption of pregnancy. Over a few days the eruption can become more widespread involving the trunk and extremities; less com-monly, annular or polycyclic lesions develop. It is thought that maternal weight gain may somehow precipitate the lesions. Anecdotally it is more often associated with male fetus pregnancy and the risk of PUPPP seems to be higher with multiple gestation pregnancies. It is important to consider other pregnancy-specific pruritic eruptions (such as pemphi-goid gestationis, intrahepatic cholestasis of pregnancy) as well as common eruptions unrelated to pregnancy (such as urticaria, drug eruptions, viral exanthems, scabies). A comprehensive examination for evidence of scabies is indicated as well as investigations to rule out pemphigoid gestationis (skin biopsy for direct immunofluoresence studies). Although PUPPP can be very symptomatic and consequently distressing for the affected mother, the eruption itself is not thought to have any adverse effects on the fetus. Management is therefore based on symptomatic relief with cool baths, light clothing, emollients and topical corticosteroids, as well as reassurance.
KEY POINTS
• Pruritic urticarial papules and plaques of pregnancy (PUPPP) is a benign pregnancy dermatosis which usually arises in the third trimester.
• The most distressing aspect of the eruption is the associated pruritus. It is otherwise self-limited with no adverse effects on fetal outcome.
• The pathomechanism of the eruption is unknown but it is more commonly observed in association with recent, sudden weight gain, male fetus and multiple gestational pregnancies.
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