Pustular Psoriasis

Diagnosis: Pustular Psoriasis

Many discrete pustules and lakes of pus on an erythematous base on legs.

Clinical Presentation

Many discrete pustules and lakes of pus on an erythematous base on legs.

Clinical History

Submitted by Alaa Saad. Originally posted September 28, 2010.

Treatment

See case discussion.

Differential Diagnosis

• Eczema/atopic dermatitis • Seborrheic dermatitis • Lichen planus • Pityriasis rosea • Tinea corporis • Secondary syphilis • Mycosis fungoides • Nummular eczema

Key Learnings

• Immune-mediated disease driven by Th17/IL-23 axis • Auspitz sign: pinpoint bleeding when scale is removed (dilated capillaries in dermal papillae) • Koebner phenomenon: lesions develop at sites of trauma • Nail involvement in ~50%: pitting, oil drop sign, onycholysis, subungual hyperkeratosis • Psoriatic arthritis develops in ~30% — screen regularly (CASPAR criteria) • Metabolic syndrome, cardiovascular disease, and depression are major comorbidities • Biologic therapy has revolutionized treatment — IL-17 and IL-23 inhibitors achieve PASI 90/100 in many patients • Histology: regular acanthosis, Munro microabscesses, dilated capillaries in dermal papillae, diminished granular layer

Tags: pustular, psoriasis, alaa saad