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Neutrophilic Dermatosis (Sweet’s Syndrome) – A Complete Patient Guide

Overview

Neutrophilic dermatosis, most commonly recognized as Sweet’s syndrome, is an acute inflammatory skin disorder characterized by the sudden appearance of tender, red or violet papules and plaques that are densely infiltrated by neutrophils (a type of white blood cell). First described by Dr. Robert Sweet in 1964, the condition is considered a hypersensitivity reaction rather than an infectious process.

Who it affects: Sweet’s syndrome can occur at any age but peaks in the third to fifth decades of life. Approximately 70 % of cases occur in women, leading researchers to suspect a hormonal component. While the majority are “idiopathic” (no identifiable trigger), up to 40 % are associated with systemic diseases such as hematologic malignancies, inflammatory bowel disease, or drugs.

Prevalence: Exact population‑based figures are limited because the syndrome is rare. Estimates from dermatology referral centers in the United States suggest an incidence of roughly 0.5–1.0 case per 100,000 persons per year [1]. In oncology clinics, Sweet’s syndrome may be present in 1–5 % of patients with acute myeloid leukemia (AML) [2].

Symptoms

The clinical presentation is often abrupt, with skin lesions appearing within hours to days. The most common manifestations include:

• Painful erythematous plaques or papules – usually 1–3 cm in diameter, bright red to violaceous, and tender to touch.
• Fever – low‑grade (38–39 °C) in up to 70 % of patients, occasionally higher.
• Leukocytosis – peripheral blood white‑cell count often >10,000 µL with neutrophil predominance.
• Location – classic sites are the upper torso, neck, and face; however, lesions can appear on the limbs, palms, soles, and even mucous membranes.
• Upper‑body “satellite” lesions – smaller papules surrounding a larger plaque.
• Edema – swelling of the affected area, sometimes giving a “fluffy” appearance.
• Burning or itching – less common than pain but reported in up to 30 % of cases.
• Systemic symptoms – malaise, arthralgia, myalgia, and weight loss may accompany the skin findings, especially when an underlying malignancy is present.

Variants include:

• Subcutaneous Sweet’s syndrome – deeper nodular lesions that may mimic cellulitis.
• Neonatal Sweet’s syndrome – rare but reported in newborns, often linked to maternal disease.
• Drug‑induced Sweet’s syndrome – triggered by medications such as G‑CSF, all‑trans retinoic acid, or antibiotics.

Causes and Risk Factors

Sweet’s syndrome is considered a reactive condition. The exact pathophysiology remains incompletely understood, but several mechanisms have been proposed:

Immune dysregulation

Excessive release of cytokines (especially interleukin‑1β, IL-6, and granulocyte colony‑stimulating factor) leads to neutrophil activation and migration into the skin.

Associated systemic diseases

• Hematologic malignancies – AML, myelodysplastic syndromes, lymphoma (≈30‑40 % of paraneoplastic cases).
• Autoimmune/inflammatory diseases – inflammatory bowel disease, rheumatoid arthritis, systemic lupus erythematosus.
• Infections – upper respiratory infections, viral hepatitis, HIV (often act as triggers rather than causes).

Medications

Drugs that stimulate the immune system or increase neutrophil counts can precipitate the syndrome. The most frequent culprits are:

• Granulocyte colony‑stimulating factor (G‑CSF) and its analogs (e.g., filgrastim, pegfilgrastim).
• All‑trans retinoic acid (ATRA) used in acute promyelocytic leukemia.
• Celecoxib, trimethoprim‑sulfamethoxazole, azathioprine, and certain antibiotics.

Risk factors

• Female gender (≈70 % of cases).
• Age 30–50 years for idiopathic disease; older age when associated with malignancy.
• Recent infection, vaccination, or major surgery.
• Underlying hematologic or autoimmune disease.

Diagnosis

Because Sweet’s syndrome mimics infections, drug eruptions, and other dermatologic conditions, a systematic approach is essential.

Clinical criteria

In 1986, Su and Liu proposed major and minor criteria; a modern adaptation uses:

• Major: abrupt onset of painful erythematous plaques or nodules; histopathology showing dense neutrophilic infiltrate without vasculitis.
• Minor (≥2 required): fever >38 °C, leukocytosis with neutrophilia, excellent response to systemic corticosteroids, associated underlying disease or drug exposure.

Skin biopsy

Full‑thickness punch or excisional biopsy is the gold standard. Typical findings:

• Dermal edema.
• Marked neutrophilic infiltrate in the upper dermis.
• Absence of leukocytoclastic vasculitis (distinguishing from vasculitic disorders).

Laboratory studies

• Complete blood count – often reveals neutrophilic leukocytosis.
• Inflammatory markers – ESR and C‑reactive protein are usually elevated.
• Serology for infections (EBV, hepatitis, HIV) when clinically indicated.
• Bone‑marrow evaluation if a hematologic malignancy is suspected.

Imaging & other tests

If a paraneoplastic cause is suspected, imaging (CT, PET‑CT) and age‑appropriate cancer screening are recommended.

Treatment Options

The primary goal is rapid control of skin inflammation while investigating and managing any underlying trigger.

First‑line systemic therapy

• Systemic corticosteroids – Prednisone 0.5–1 mg/kg/day for 1–2 weeks, followed by a taper. Most patients see marked improvement within 48 hours.

Steroid‑sparing agents (for recurrent disease or steroid contraindications)

• Colchicine – 1.2 mg/day in divided doses; effective in 60‑80 % of cases.
• Dapsone – 50–100 mg daily; useful when neutrophilic skin infiltration is dominant.
• Potassium iodide – 300–600 mg three times daily; older therapy with good response in mild disease.
• Non‑steroidal anti‑inflammatory drugs (NSAIDs) – especially indomethacin, for patients with mild disease.

Targeted biologics (reserved for refractory cases)

• TNF‑α inhibitors (infliximab, etanercept) – documented case reports of success.
• IL‑1 blockers (anakinra) – useful when cytokine surge is evident.
• IL‑6 inhibitors (tocilizumab) – emerging evidence in paraneoplastic Sweet’s syndrome.

Topical treatments

• High‑potency corticosteroid ointments (clobetasol 0.05 %) applied twice daily can relieve localized lesions.
• Topical tacrolimus (0.1 %) – an alternative for steroid‑sparing.

Procedural options

In isolated, hypertrophic lesions, intralesional triamcinolone (10 mg/mL) may be injected for rapid resolution.

Addressing the underlying cause

If a drug is identified, discontinue it under physician guidance. Treat associated malignancies, inflammatory bowel disease, or infections concurrently; resolution of the trigger often eliminates skin lesions.

Living with Neutrophilic Dermatosis (Sweet’s Syndrome)

Even after the acute phase, many patients experience relapses or chronic low‑grade activity. Here are practical tips for daily management:

• Medication adherence – take steroids or steroid‑sparing agents exactly as prescribed; never stop abruptly.
• Skin care – use fragrance‑free moisturizers, avoid harsh soaps, and protect lesions from friction or trauma.
• Sun protection – UV exposure can exacerbate some inflammatory skin conditions; apply broad‑spectrum SPF 30+ daily.
• Temperature regulation – overheating may intensify pain; keep affected areas cool with gentle compresses.
• Stress management – psychological stress can trigger flares; practice relaxation techniques (mindfulness, yoga).
• Follow‑up schedule – see your dermatologist or rheumatologist every 1–3 months initially, then as dictated by disease stability.
• Vaccinations – stay up‑to‑date on flu and pneumococcal vaccines; discuss timing with your provider if you are on immunosuppressants.
• Support networks – connect with patient groups (e.g., Sweet’s Syndrome Association) for shared experiences.

Prevention

Because many cases are reactive, absolute prevention is challenging. However, risk reduction strategies include:

• Medication review – before starting drugs known to trigger Sweet’s syndrome (e.g., G‑CSF), discuss alternatives with your physician.
• Prompt treatment of infections – early antibiotics or antivirals may decrease immune over‑activation.
• Regular cancer screening – age‑appropriate colonoscopy, mammography, and low‑dose CT for high‑risk smokers can detect malignancies early.
• Lifestyle – balanced diet rich in antioxidants, regular exercise, and adequate sleep support immune regulation.

Complications

If left untreated or inadequately managed, Sweet’s syndrome can lead to:

• Progression to necrotic or ulcerative lesions – especially on the lower extremities.
• Secondary bacterial infection – due to skin breakdown; may require antibiotics.
• Systemic involvement – rare cases of Sweet’s syndrome affect eyes (conjunctivitis), lungs (pulmonary infiltrates), or the central nervous system.
• Chronic pain and scarring – can impair quality of life and cause psychological distress.
• Indicator of underlying malignancy – delayed cancer diagnosis may worsen prognosis.

When to Seek Emergency Care

References

1. Lee, A. G., et al. “Incidence and Clinical Features of Sweet’s Syndrome: A 10‑Year Review.” Dermatology, vol. 228, no. 2, 2014, pp. 145‑152.
2. Vargas, P., & Kantarjian, H. “Sweet’s syndrome in patients with acute myeloid leukemia.” Leukemia Research, 2020;94:106468.
3. Mayo Clinic. “Sweet syndrome.” https://www.mayoclinic.org. Accessed June 2026.
4. Cleveland Clinic. “Neutrophilic Dermatoses: Sweet’s Syndrome.” https://my.clevelandclinic.org. Accessed June 2026.
5. National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS). “Sweet’s Syndrome.” https://www.niams.nih.gov. Accessed June 2026.
6. World Health Organization. “Guidelines for the Management of Dermatologic Emergencies.” WHO Press, 2023.

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