Urticaria Pigmentosa

Diagnosis: Urticaria Pigmentosa

Multiple pigmented macule

Clinical Presentation

Multiple pigmented macule

Clinical History

Submitted by Saifuzzaman Yusoff. Originally posted June 15, 2011.

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: urticaria, pigmentosa, saifuzzaman yusoff