(BMJ)—A 40-yo woman (gravida 2, para 2) presented 9 days postpartum w/ a 4-day hx of itchy rash that started on her limbs and progressed to her trunk, abdomen, and back. No meds. Exam: tense, fluid-filled blisters on limbs (palms/soles spared), w/ diffuse erythematous plaques on torso. Nikolsky sign neg. What is the dx?
Impetigo herpetiformis
Erythema multiforme
Pemphigoid gestationis
Polymorphic eruption of pregnancy
Epidermolysis bullosa
You are correct. Bx confirmed the typical clinical picture of pemphigoid gestationis, an autoimmune condition thought to be caused by an atypical expression of major histocompatibility class II antigens in the placenta. Pemphigoid gestationis was previously known as herpes gestationis but bears no affiliation w/ the herpes virus. Systemic steroids are the mainstay of tx; antihistamines are used for pruritus. This pt was weaned off steroids over 4wk, w/ full recovery.

BMJ 2017;356:j968