What is Sweet syndrome (Acute Febrile Neutrophilic Dermatosis)?

From the Guidelines

Systemic corticosteroids are the most effective treatment for Sweet syndrome, as they have been reported to be effective in managing the condition 1. Sweet syndrome, also known as acute febrile neutrophilic dermatosis, is a rare inflammatory skin condition characterized by tender, red inflammatory nodules or papules, usually affecting the upper limbs, face or neck. The condition is part of the group of acute neutrophilic dermatoses and can be distinguished by its appearance, distribution, and histological features. Some key characteristics of Sweet syndrome include:

• A strong predilection for women and patients with colonic involvement and other extraintestinal manifestations 1
• A rash that is mostly associated with active disease 1
• The need for treatment of any underlying cause, as Sweet syndrome can be associated with various conditions 1 The primary treatment for Sweet syndrome is systemic corticosteroids, which usually produces rapid improvement within a short period. It's essential to note that:
• The rash is mostly associated with active disease, and treatment should be focused on managing the underlying condition 1
• Systemic corticosteroids have been reported to be effective in managing Sweet syndrome, making them the first line of treatment 1

From the Research

Definition and Characteristics of Sweet Syndrome

• Sweet syndrome is a dermatological condition characterized by pyrexia, elevated neutrophil count, painful erythematous cutaneous lesions, and a diffuse infiltrate consisting predominantly of mature neutrophils typically located in the upper dermis 2, 3.
• The syndrome can be classified into three clinical settings: classical or idiopathic Sweet's syndrome, malignancy-associated Sweet's syndrome, and drug-induced Sweet's syndrome 2, 3.
• Sweet syndrome presents with a constellation of clinical symptoms, physical features, and pathologic findings, including fever, neutrophilia, tender erythematous skin lesions, and a diffuse infiltrate consisting predominantly of mature neutrophils 3.

Treatment Options for Sweet Syndrome

• Systemic corticosteroids are considered the 'gold standard' for the treatment of patients with Sweet's syndrome 2, 3, 4.
• Other effective treatment options include potassium iodide, colchicine, indomethacin, clofazimine, cyclosporine, and dapsone 2, 3, 4.
• Topical application of high potency corticosteroids or intralesional corticosteroids may be efficacious for treating localized lesions 2, 3, 4.
• In some cases, the symptoms and lesions of Sweet's syndrome may resolve spontaneously without any therapeutic intervention 2, 3.

Association with Inflammatory Bowel Disease and Malignancy

• Sweet syndrome is associated with inflammatory bowel disease (IBD) and azathioprine use 5.
• The syndrome can precede or occur with IBD diagnosis in almost one-third of cases 5.
• Malignancy-associated Sweet's syndrome (MA-SS) is a distinct entity that requires early diagnosis and detection of concomitant malignancy to improve patient outcomes 6.
• Azathioprine-associated Sweet's syndrome is also a distinct entity with different clinical characteristics and treatment outcomes compared to non-azathioprine-associated Sweet's syndrome 5.

Clinical Manifestations and Extracutaneous Associations

• Sweet syndrome can present with extracutaneous manifestations, including fever, neutrophilia, and inflammatory bowel disease 3, 5.
• The syndrome can also be associated with malignancy, particularly acute myelogenous leukemia 3.
• Clinical manifestations of Sweet syndrome can vary, including tender plaques and nodules, fever, and leukocytosis 6.