Differential Diagnosis for Pustulous Acné Outbreak with Leucocytosis

Single Most Likely Diagnosis

• Acne Fulminans: This is a severe form of acne that presents with sudden onset of highly inflammatory, painful, and destructive acne lesions, often accompanied by systemic symptoms such as fever and leucocytosis. The presence of pustulous acne outbreak and leucocytosis makes this a highly plausible diagnosis.

Other Likely Diagnoses

• Severe Acne Vulgaris: While not as severe as acne fulminans, severe acne vulgaris can present with numerous pustules and may be associated with systemic inflammation, including leucocytosis, especially if there is a significant bacterial infection component.
• Folliculitis: An inflammatory condition of the hair follicles, which can be caused by bacterial, viral, or fungal infections. It can present similarly to acne and may cause leucocytosis if the infection is severe.
• Perioral Dermatitis: Although it typically presents around the mouth, it can sometimes resemble acne and may be accompanied by systemic signs of inflammation in severe cases.

Do Not Miss Diagnoses

• Staphylococcal Scalded Skin Syndrome (SSSS): A potentially life-threatening condition caused by staphylococcal toxins that can present with skin lesions and systemic symptoms, including leucocytosis. Early recognition is crucial.
• Toxic Epidermal Necrolysis (TEN): A severe skin condition usually triggered by medications, leading to widespread skin necrosis and detachment. It can initially present with nonspecific symptoms, including leucocytosis, and is a medical emergency.
• Septicemia: Bacterial infection in the blood can cause a wide range of skin manifestations, including pustules, and is always accompanied by systemic signs of infection, such as leucocytosis. Identifying and treating the underlying cause is critical.

Rare Diagnoses

• Sweet Syndrome (Acute Febrile Neutrophilic Dermatosis): Characterized by the sudden onset of fever, leucocytosis, and tender, erythematous, well-demarcated papules and plaques. It's a rare condition but can mimic severe acne outbreaks.
• Pyoderma Gangrenosum: A rare skin condition that can start as a pustule and progress to a painful nodule or ulcer. It's often associated with systemic diseases and can present with leucocytosis due to the significant inflammatory response.
• Erythema Elevatum Diutinum: A rare skin condition characterized by red, purple, or brown lesions that can resemble acne. It's associated with various infections and systemic diseases and may present with leucocytosis.