Pruritic urticarial papules and plaques of pregnancy (polymorphic eruption of pregnancy)

Diagnosis: Pruritic urticarial papules and plaques of pregnancy (polymorphic eruption of pregnancy)

Small papules distributed and confluent within striae distensae on the abdomen in a pregnant lady.

Clinical Presentation

Small papules distributed and confluent within striae distensae on the abdomen in a pregnant lady.

Clinical History

Submitted by Alaa Saad. Originally posted October 30, 2010.

Treatment

See case discussion.

Differential Diagnosis

• Urticarial vasculitis • Drug eruption • Contact dermatitis • Erythema multiforme • Bullous pemphigoid (urticarial phase) • Insect bites (papular urticaria) • Dermatographism • Mastocytosis

Key Learnings

• Individual wheals resolve within 24 hours without residual marks — if lasting >24 hours, consider urticarial vasculitis • Acute urticaria (6 weeks): usually idiopathic; autoimmune mechanism in ~40% • CSU workup: CBC, ESR/CRP, TSH; extensive testing is low-yield • Omalizumab (anti-IgE) is FDA-approved for CSU refractory to antihistamines • Angioedema: deeper involvement — ACE inhibitor-induced angioedema is bradykinin-mediated (antihistamines won't work) • Second-generation antihistamines at up to 4× standard dose before escalating therapy

Tags: pruritic, urticarial, papules, and, plaques, pregnancy, polymorphic, eruption, alaa saad