Diagnosis. A biopsy is necessary for the definitive diagnosis. Direct immunofluorescence (DIF) microscopy of a sample of perilesional skin can show tissue-bound immunoreactants. Linear deposition of the complement component protein C3 along the basement membrane zone is diagnostic for PG. IgG is also deposited about 40% of the time.3 Serum enzyme-linked immunosorbent assay (ELISA) studies are also helpful in diagnosis. They have excellent sensitivity and specificity, as well as the capacity to monitor levels of antibody, which correlate with the severity of disease.1
Treatment. Oral corticosteroids are the first-line treatment for PG, typically 20 to 60 mg per day of prednisone. Oral corticosteroids are typically most effective in ameliorating the patient’s symptoms. Prednisone at doses of 40 to 80 mg per day for a short time has not been associated with congenital abnormalities.6 PG patients can also be treated successfully with intravenous immunoglobulin (IVIG) and cyclosporine in refractory cases.7
Pruritus associated with this condition can interfere with day-to-day activity and with the patient’s ability to sleep. Patients may also complain that the rash is painful, particularly if bullae rupture, leading to superficial ulcerations. Fortunately, the patient’s quality of life can be dramatically improved with systemic corticosteroids—with no significant risk to the fetus.
Sequelae. PG uniformly resolves within a few weeks, but the mother’s autoantibodies can passively be transferred to the fetus, causing vesicles and bullae in the newborn.8 An increased incidence of small-for-gestational age (SGA) infants has also been noted in PG, although no lasting morbidity or mortality in the offspring has been noted.5 This disease tends to recur with future pregnancies, but will skip a pregnancy 8% of the time.5
FIGURE 1
Pemphigoid gestationis
Pruritic urticarial papules and plaques of pregnancy
This condition is known by many names besides PUPPP: polymorphic eruption of pregnancy, toxemic erythema of pregnancy, and late prurigo of pregnancy.1 It is a pruritic, inflammatory skin disorder that has been variously estimated to occur in anywhere from 1 in 120 to 1 in 240 pregnancies.8 PUPPP is second only to eczema as the most common dermatosis of pregnancy.
Presentation. As the name implies, the lesions of PUPPP are itchy, red papules that often coalesce into plaques (FIGURE 2). The lesions usually occur in primigravidas after the 34th week of gestation, although they may be seen at any time from the first trimester through the postpartum period.9
Lesions are classically found on the abdomen, sparing the umbilical area, and are found primarily in the striae. This distribution helps to differentiate PUPPP from PG, where the lesions typically cluster around the umbilicus. Most PUPPP lesions (80% in 1 study) are dispersed on the abdomen, legs, arms, buttocks, chest, and back. Another 17% appear only on the abdomen and proximal thighs, and the remaining 3% on the limbs.10 Nearly 50% of the time, lesions also include discrete vesicles.11 There are no reported cases of mucosal involvement.
Patients with this condition are often very uncomfortable. The associated pruritus is severe enough to interfere with sleep. Despite the itching, however, lesions are seldom excoriated.
Pathophysiology. The disorder has been strongly associated with maternal weight gain and multiple gestations. One working hypothesis is that rapid abdominal distention observed in the third trimester leads to damage of the connective tissue, which then releases antigenic molecules, causing an inflammatory reaction.12 Another hypothesis is that increased levels of fetal DNA that have been detected in the skin of PUPPP patients may contribute to the pathology. One study detected male DNA in 6 of 10 PUPPP sufferers, but found none in any of 26 controls— pregnant women without PUPPP pathology.5 There is some evidence that patients with atopy may be predisposed to PUPPP, as well as patients who are hypertensive or obese.10,13
Differential. Initially, PUPPP lesions can be difficult to differentiate from urticarial PG lesions. The distribution of the lesions is the best clue: PG lesions cluster around the umbilicus, whereas PUPPP lesions uniformly spare the umbilical area. Additional disorders in the PUPPP differential are atopic dermatitis, superficial urticarial allergic eruption, viral exanthema, and contact or irritant dermatitis.
Diagnosis. PUPPP can only be diagnosed through clinical observation. None of the available laboratory tests—immunofluorescence, histology, serology—yield findings specific for PUPPP, although histology and immunofluorescence can readily differentiate between this condition and PG.
Treatment. Because the disease holds no real danger for mother or fetus, treatment can be aimed solely at symptomatic relief. Mild to potent topical steroids (consider triamcinolone or fluocinonide) should relieve pruritus within 48 to 72 hours.8 Antihistamines and occasionally low-dose systemic steroids may also be used. Consider hydroxyzine, although diphenhydramine has the more proven safety profile in pregnancy.