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.
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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.
