How does pemphigoid gestationis (PG) present?
What are the risks to the mother and the fetus with PG?
How do you diagnose PG?
What are the recommendations for management of PG?
A 28-year-old primiparous woman presents during her second trimester with periumbilical urticarial papules and plaques with minimal vesiculation. In addition, she has pruritic urticarial papules and plaques on her trunk and proximal extremities. The lesions are increasing in number and have failed to improve with over-the-counter topical hydrocortisone products. A biopsy demonstrates intense eosinophil infiltration of the dermis, with direct IF identifying antibody deposition along the basement membrane of the skin. Thus a diagnosis of PG is confirmed (Figs. 25-1 and 25-2).
Urticarial papules and plaques involving the trunk. (Used with permission from Luca Borradori.)
Proximal lower extremities in PG. (Used with permission from Luca Borradori.)
Pemphigoid gestationis (PG) is a variant of bullous pemphigoid, in which the patient has circulating autoantibodies against proteins in the basement membrane of the skin, resulting in pruritus, rash, and blisters. Previously termed herpes gestationis, PG is not infectious, and thus this old terminology has been abandoned. While PG is considered to be a dermatosis limited to pregnancy, some rare cases have been associated with either choriocarcinoma, hydatidiform moles, or trophoblastic tumors.
PG occurs in approximately 1 out of 1700 to 50,000 pregnancies,1 with half the cases developing in the first pregnancy. Patients with PG have an increased incidence of autoimmune diseases, particularly autoimmune thyroid disorders.2 The HLA-DR3 and DR4 alleles have been associated with the development of PG.3,4 While the role of different partners with the same mother had previously been considered to be one potential causative factor, a larger study failed to support this theory.5,6
PG is classically characterized as a pruritic papulovesicular eruption that favors periumbilical skin. The trunk and extremities can be affected, with sparing of the mucous membranes.1,5 Lesions typically begin as urticarial plaques and can be clinically and histologically identical to those observed in polymorphous eruption of pregnancy. Frank blistering is not a requisite.5
PG most commonly occurs during the second trimester of pregnancy, though it has been described as occurring from the second week of gestation to the early postpartum period.1,5 Interestingly, with each subsequent pregnancy, the disease recurs with earlier onset, but 8% of mothers experience a skip pregnancy, where they have an unaffected pregnancy following a previously affected one.5,7