Sweet's syndrome

Overview

Sweet's syndrome, also known as acute febrile neutrophilic dermatosis, is a rare inflammatory skin condition characterized by the rapid onset of painful, red plaques or nodules accompanied by fever and elevated white blood cell count. It was first described by Dr. Robert Douglas Sweet in 1964.

This syndrome is considered an immune-mediated disorder involving an abnormal accumulation of neutrophils in the skin and sometimes internal organs. Sweet’s syndrome can occur as a primary idiopathic condition or secondary to infections, malignancies, autoimmune diseases, or drug exposure.

Causes

The exact cause of Sweet's syndrome is not fully understood, but several triggering factors and associations have been identified:

• Idiopathic: No identifiable cause in many cases.

• Infections: Upper respiratory tract infections, gastrointestinal infections, and others can trigger the syndrome.

• Malignancies: Particularly hematologic cancers such as acute myelogenous leukemia, myelodysplastic syndrome, and lymphomas.

• Autoimmune diseases: Such as inflammatory bowel disease, rheumatoid arthritis, and lupus.

• Medications: Drugs like granulocyte colony-stimulating factor (G-CSF), antibiotics, and others have been implicated.

Symptoms

Symptoms typically develop suddenly and include:

• Fever and malaise

• Painful, tender, raised red or purple skin lesions—often plaques or nodules

• Lesions commonly appear on the face, neck, upper limbs, and trunk

• Swelling and warmth over affected areas

• Possible involvement of mucous membranes

• Systemic symptoms such as joint pain or eye inflammation in some cases

Diagnosis

Diagnosis is clinical, supported by laboratory and histopathological findings:

• Skin biopsy: Shows dense infiltration of neutrophils in the upper dermis without evidence of infection.

• Blood tests: Elevated white blood cell count, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP).

• Exclusion of infections: Cultures and stains to rule out infectious causes of skin lesions.

• Identification of underlying triggers: Through detailed history, physical examination, and appropriate investigations.

Treatment

Treatment focuses on controlling inflammation and addressing underlying causes:

• Corticosteroids: Systemic steroids such as prednisone are the mainstay, typically producing rapid improvement.

• Alternative therapies: Colchicine, dapsone, or potassium iodide may be used if steroids are contraindicated or ineffective.

• Treatment of underlying disease: Managing infections, malignancies, or autoimmune conditions associated with Sweet's syndrome.

• Symptomatic care: Pain relief and wound care for skin lesions.

Prognosis

The prognosis of Sweet's syndrome is generally good with appropriate treatment. Most patients respond rapidly to corticosteroids and recover without permanent skin damage. However, relapse is common, especially if underlying conditions are not controlled.

Prognosis depends largely on the presence and severity of associated diseases. Close follow-up is essential to monitor for recurrence and manage any systemic involvement.