A 45-year-old woman presents with a 4-day history of fever and painful red plaques on her face, neck, upper extremities, and chest pictured below. 

Laboratory studies show leukocytosis with neutrophilia and elevated inflammatory markers. A punch biopsy shows a dense neutrophilic infiltrate in the upper dermis with prominent papillary dermal edema and no evidence of vasculitis. Bacterial and fungal cultures are negative so far - she recently recovered from an upper respiratory infection. 

What is the most appropriate initial treatment?

A. Oral dapsone
B. Oral corticosteroids
C. Topical high-potency corticosteroids
D. Intravenous antibiotics
E. Methotrexate

Rationale: 

This patient’s presentation is classic for Sweet syndrome, also known as acute febrile neutrophilic dermatosis, which is characterized by the sudden onset of painful, erythematous, and edematous plaques or nodules. Systemic symptoms such as fever and malaise are common. Laboratory findings typically reveal neutrophilia. Histologically, a dense neutrophilic infiltrate is seen in the dermis and frequently shows papillary dermal edema. Infections can present similarly both clinically and histologically and neutrophilic dermatoses are often viewed as a diagnosis of exclusion. Sweet syndrome may be idiopathic or associated with underlying malignancy, infections, inflammatory diseases such as inflammatory bowel disease, or medications. Physicians should explore potential causes once a diagnosis is made. 

Correct answer: B. Oral corticosteroids

Oral corticosteroids are the treatment of choice for Sweet syndrome as patients typically respond rapidly with improvement in systemic symptoms and cutaneous lesions within 48 to 72 hours. The standard dose of prednisone is 0.5-1 mg/kg per day followed by a gradual taper once symptoms resolve. 

Incorrect answer choices: 

A. Dapsone

While dapsone is effective in treating various neutrophilic dermatoses, it is not considered first-line therapy for Sweet syndrome. Dapsone is used for patients who cannot tolerate systemic corticosteroids or require a steroid-sparing agent for long-term management.

C. Topical corticosteroids

Although topical corticosteroids could be used for mild/localized cases, it would not be appropriate as first-line therapy in our patient given her extensive involvement and systemic symptoms.

D. Intravenous antibiotics 

Sweet syndrome can often be misdiagnosed as a skin infection due to the abrupt onset, erythema, and tenderness. However, the absence of systemic toxicity, negative cultures, and supportive histopathology makes infection unlikely in our patient. Initiating antibiotics in such cases delays appropriate treatment and can expose the patient to unnecessary medication-related risks.

E. Methotrexate

Methotrexate could be appropriate for recurrent or steroid-refractory Sweet syndrome. However, it is not appropriate as initial therapy for an acute presentation given that it has a slower onset of action.

Additional reading at Fitzpatrick's Dermatology Chapter 36: Sweet Syndrome