PRURITIC URTICARIAL PAPULES AND PLAQUES OF PREGNANCY
Pruritic urticarial papules and plaques of pregnancy (PUPPP), also known as polymorphous eruption of pregnancy (PEP), is the most common dermatosis associated with pregnancy. The name describes the variable appearance that the rash can take. Idiopathic in nature, it is seen most commonly during an expectant mother’s first pregnancy. It has been shown to have no bearing on pregnancy outcome or on the fetus or newborn. It is diagnosed on clinical grounds and rarely biopsied. There are no associated laboratory abnormalities. The classic history and variable morphology of the rash are characteristic.
Clinical Findings: PUPPP occurs during the late third trimester of pregnancy or has its onset soon after delivery. The rash almost always begins within the striae distensae of the abdomen. Small urticarial papules and plaques begin to form within the striae. They are extremely pruritic and cause significant discomfort. As the name implies, the rash can have a polymorphous nature. Papules, plaques, macules, and even small vesicles have been described. The rash may spread from the abdomen to other regions of the body. PUPPP has been described to occur more commonly during the first pregnancy with a male fetus. The reasons for this are unknown. The rash spontaneously remits after delivery, in most cases within 2 to 4 weeks. Those patients with onset after delivery typically have a shorter course, with 1 week of severe itching followed by remission soon afterward. PUPPP typically does not recur in subsequent pregnancies. PUPPP also does not flare when birth control medications are started, as does herpes gestationis.
The main differential diagnosis is between PUPPP and prurigo gestationis. Prurigo gestationis has no primary lesions and manifests as diffuse itching with excoriations. Liver function enzymes may be elevated in this condition. Prurigo gestationis is associated with an increased risk for prematurity. Scabies infection can also be highly pruritic and can be considered in the differential diagnosis. Scabies is easily diagnosed with a scraping and microscopic evaluation of a burrow. Scabies can have its onset at any time during a pregnancy, and urticarial papules and plaques within striae are not typically seen. If they are seen, they are not as numerous or uniform in appearance as the lesions of PUPPP. Herpes gestationis, also known as pemphigoid gestationis or bullous pemphigoid of pregnancy, is the most severe of all the pregnancy-associated rashes. It can begin as urticarial red plaques on the abdomen and then spread to other regions. Compared with PUPPP, it tends to occur earlier in the pregnancy. The biggest differentiating point is that the rash of herpes gestationis will begin to blister: Small vesicles form and quickly coalesce into larger bullae. Bullae are never seen in PUPPP. Herpes gestationis is caused by maternal anti- body formation against hemidesmosomal antigens. Titer levels can be measured, and the most commonly found antibody is against the 180-kd bullous pemphigoid antigen (BP180). There is a risk of prematurity and low birth weight with this rash. Oral corticosteroids are often needed to keep herpes gestationis under control. The rash remits after delivery but tends to recur during subsequent pregnancies, and it can flare when an affected patient starts taking birth control medications.
Pathogenesis: The etiology is unknown. PUPPP is most commonly seen in first pregnancies and possibly is more common in multiple-birth pregnancies. The exact roles played by skin distention, hormonal changes, and interactions with the immune system in the pathogenesis of PUPPP are being studied.
Histology: Histological findings of PUPPP biopsy specimens are nonspecific; there is a superficial and deep perivascular lymphocytic infiltrate. Occasional eosinophils are seen, with some dermal edema.
Treatment: The main treatment for PUPPP is to give supportive care and to try to suppress the itching symptoms. There are no ill effects on the fetus, and expectant mothers can be given topical medium or high-potency corticosteroids to help decrease the itching. Occasionally, antihistamines such as diphenhydramine are also needed to control the itching.