Diagnosing Sweet Syndrome

Clinical Presentation and Diagnostic Criteria

Sweet syndrome presents with a characteristic triad of tender, erythematous papules, nodules, or plaques, fever, and neutrophilia, with skin lesions commonly appearing on the upper limbs, trunk, and head/neck, according to the Journal of Crohn's and Colitis 1
Inflammatory bowel disease is associated with Sweet syndrome, as reported in the Journal of Crohn's and Colitis 1

The differential diagnosis should include drug eruption, cutaneous infiltration with underlying malignancy, chemotherapy or radiation-induced skin reactions, erythema multiforme, leukocytoclastic vasculitis, and infection, as cited in Clinical Infectious Diseases 2
Infection, including bacterial, fungal, viral, or parasitic, should be considered in the differential diagnosis, as mentioned in Clinical Infectious Diseases 2 and 3

A thorough clinical examination of skin lesions should be performed, as recommended in Clinical Infectious Diseases 3
Skin biopsy is essential for definitive diagnosis and should be performed on an active lesion, as cited in Clinical Infectious Diseases 2 and 3
Failure to perform skin biopsy can lead to misdiagnosis, as noted in Clinical Infectious Diseases 2 and 3

Mycoplasma pneumoniae has been specifically associated with a variant of Sweet syndrome involving predominantly mucous membranes, in patients with upper respiratory tract infections 4

Skin lesions in Sweet syndrome develop over 24-48 hours with potential for recurrence, and thorough clinical examination must identify distribution and morphology of skin lesions, distinguishing from bowel-associated dermatosis-arthritis syndrome by upper limb distribution and lack of ulceration 5
The syndrome can be distinguished from other conditions such as pyoderma gangrenosum by the absence of ulceration and necrosis, and from erythema multiforme and leukocytoclastic vasculitis by the characteristic dense dermal neutrophilic infiltrate 5

50-70% of Sweet syndrome cases are associated with underlying systemic disorders, including inflammatory bowel disease, which forms part of the spectrum of neutrophilic dermatoses in IBD, and requires evaluation 5, 6

The American Gastroenterological Association recommends evaluating patients with Sweet syndrome for underlying inflammatory bowel disease, particularly ulcerative colitis and Crohn's disease 6