An unusual acute erythrodermic rash

A 50-year-old woman with a history of mild atopic dermatitis presented to the emergency department (ED) for evaluation of a new rash slowly worsening over 3–4 weeks. She had erythematous patches and plaques with desquamating scale that together involved over 80% of her body surface area (Figure 1). It spared her palms, soles, and mucosa (Figures 2 and 3). She reported no new medications or exposures. Shortly after the rash started, topical ketoconazole and permethrin were prescribed without benefit. Basic lab tests were unremarkable except for mild leukocytosis. She was admitted for dermatologic consult and discharged with outpatient follow-up after a skin biopsy and initiation of topical erythrodermic protocol. The clinicopathologic correlation fit best with erythrodermic psoriasis. No triggers were identified, and her skin improved over the following month with standard psoriasis treatment.

A rare condition among those with psoriasis, erythrodermic psoriasis is the least common psoriatic subtype accounting for 3% of all psoriatic conditions. Common triggers include sunburn, alcohol, and infection. COVID-19 vaccination has also been reported as a possible trigger.¹

Diagnosing erythrodermic psoriasis requires at least 75% body surface area involvement and biopsy findings of lymphocytic and eosinophilic perivascular infiltrates as well as dilated capillaries and hyperkeratosis.² The clinical differential diagnosis included staph scalded skin syndrome, as well as Steven Johnson Syndrome/Toxic Epidermal Necrolysis (SJS/TEN) and Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS).

Cyclosporine and methotrexate are first-line pharmacologic treatment options for erythrodermic psoriasis, and the majority of patients achieve remission within 2–4 months.³

The authors declare no conflicts of interest.