A 45-year-old woman with recently diagnosed acute myeloid leukaemia develops sudden-onset painful, oedematous, erythematous-violaceous plaques on the arms and face with fever and neutrophilia >8000/mm³. Skin biopsy shows dense dermal neutrophilic infiltrate without vasculitis. What is the diagnosis and its pathognomonic treatment response?
- A Pyoderma gangrenosum; dramatic response to cyclosporine
- B Sweet's syndrome (acute febrile neutrophilic dermatosis); dramatic response to systemic corticosteroids ✓
- C Leukocytoclastic vasculitis; response to dapsone
- D Erythema multiforme; self-limiting within 4–6 weeks
Correct answer: B. Sweet's syndrome (acute febrile neutrophilic dermatosis); dramatic response to systemic corticosteroids
Explanation
Sweet's syndrome (acute febrile neutrophilic dermatosis) presents with painful erythematous plaques, fever, and neutrophilia; histology shows a dense dermal neutrophilic infiltrate WITHOUT leukocytoclastic vasculitis. It is associated with haematological malignancies (especially AML), inflammatory bowel disease, and infection. The hallmark is a dramatic, rapid response to systemic corticosteroids (prednisolone 1 mg/kg/day). Pyoderma gangrenosum shows ulceration with undermined violet edges.
Reference: Neena Khanna Illustrated Synopsis of Dermatology & STD, 6th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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