The patient had pemphigoid gestationis, also known as herpes gestationis, a rare autoimmune bullous disease of pregnancy and the puerperium.1 Clinically and immunopathologically, pemphigoid gestationis is related to the pemphigoid group of disorders and is not virally mediated.2
FAST TRACK
When there are no blisters, it is impossible to distinguish pemphigoid gestationis from other cutaneous eruptions of pregnancy
In the United States, pemphigoid gestationis has an incidence of 1:10,000 to 1:50,000 pregnancies.3 Clinically, it manifests during the second or third trimester, with a sudden onset of extremely pruritic urticarial papules and plaques usually located around the umbilicus. These lesions often progress to tense vesicles and blisters and spread peripherally to the trunk, often sparing the face, palms, and soles.4 Worsening of the lesions at the time of delivery occurs in 75% of cases, and usually recurs with subsequent pregnancies.5 Occasionally, however, subsequent pregnancies are unaffected, so-called “skip pregnancies.”6 This occurs most often when there has been a change in paternity.7
The exact cause of pemphigoid gestationis is unknown. Investigative efforts lead to the identification of an immunoglobulin G (IgG) autoantibody, which binds to bullous pemphigoid (BP) antigen 2, also called BP180, which is a protein associated with hemidesmosomes of basal keratinocytes.8-10 These hemidesmosomes form the central portion of the dermalepidermal anchoring complex, whose function is to establish a connection between the basal keratinocytes and the upper dermis.11,12 This is critical for maintaining dermal-epidermal adhesion. It is hypothesized that binding of autoantibodies to BP180 initiates an inflammatory reaction, leading to blister formation at the dermal-epidermal junction.13
