Differential Diagnosis for Erythematous Plaque with Central Ulcer and Blistering

Single Most Likely Diagnosis

• Eczema herpeticum: This condition is a spread of the herpes simplex virus within an area of skin affected by atopic dermatitis (eczema), leading to the formation of small, itchy, blistering rash which can progress to erythematous plaques with central ulcers and blistering.

Other Likely Diagnoses

• Impetigo: A highly contagious skin infection that can cause red sores, ulcers, and blistering, often starting as a single lesion that can spread.
• Erysipelas: An acute infection of the upper dermis and superficial lymphatics, typically caused by beta-hemolytic group A Streptococcus, presenting with well-demarcated, erythematous, and sometimes blistering lesions.
• Contact dermatitis: An inflammatory skin reaction that occurs when the skin comes into contact with an irritant or allergen, potentially leading to erythematous plaques, ulcers, and blistering in severe cases.

Do Not Miss Diagnoses

• Necrotizing fasciitis: A severe infection that destroys the tissue under the skin, including fat and the tissue covering the muscles (fascia), which can start with erythema, blistering, and ulcers but rapidly progresses to severe pain and necrosis.
• Meningococcemia: A severe infection caused by Neisseria meningitidis, which can present with a petechial or purpuric rash that may blister and ulcerate, often accompanied by severe systemic symptoms.
• Staphylococcal scalded skin syndrome (SSSS): Caused by staphylococcal toxins that strip the skin of its outer layer, leading to widespread blistering and peeling, starting with erythematous plaques.

Rare Diagnoses

• Sweet syndrome (Acute febrile neutrophilic dermatosis): Characterized by the sudden onset of fever, leukocytosis, and tender, erythematous, well-demarcated papules and plaques that may blister or ulcerate.
• Pyoderma gangrenosum: A rare skin condition that leads to the formation of large, painful ulcers, often starting as a small pustule or blister that breaks down to form an ulcer.
• Cutaneous leishmaniasis: Caused by Leishmania parasites, transmitted by sandflies, leading to skin lesions that can ulcerate and may have a raised edge, though typically not described with the initial presentation of an erythematous plaque with central ulcer and blistering.