Sweet syndrome in patients with and without malignancy: A retrospective analysis of 83 patients from a tertiary academic referral center

Background: Sweet syndrome is a neutrophilic dermatosis that may be categorized into classic, malignancy-associated, and drug-induced subtypes. Few studies have systematically analyzed this rare disorder. Objective: To describe the clinicopathologic characteristics and treatment of Sweet syndrome and identify characteristics associated with concurrent malignancy. Methods: We retrospectively reviewed patients with Sweet syndrome at the University of Pennsylvania from 2005 to 2015. Results: We identified 83 patients (mean age, 57 years; 51% male) with Sweet syndrome: 30% with the classic form, 44% with the malignancy-associated form, 24% with the drug-induced form in the setting of malignancy, and 2% with the drug-induced form. Acute myeloid leukemia was the most common malignancy (in 24 of 83 patients [29%]). Filgrastim was the most common medication (used in 8 of 83 patients [10%]). Leukopenia (P <.001), anemia (P =.002), thrombocytopenia (P <.001), absence of arthralgia (P <.001), and histiocytoid or subcutaneous histopathology (P =.024) were associated with malignancy (χ² test). Limitations: This was a retrospective study that represents patients from a single tertiary academic referral center, which may limit its generalizability to other settings. Conclusion: When caring for patients with Sweet syndrome, dermatologists should be aware of the potential association of leukopenia, anemia, thrombocytopenia, absence of arthralgia, and histiocytoid or subcutaneous histopathology with malignancy.