Characteristics of Sweet syndrome in patients with or without malignancy

Sweet syndrome is a neutrophilic dermatosis occasionally associated with malignancies. Due to its rarity, the clinical features of Sweet syndrome are still unclear. Thus, we aimed to analyze clinical features, treatment, and outcomes of these patients according to associated disease. We conducted a retrospective, longitudinal cohort study from January 2000 to August 2020. We reviewed the medical records of 52 patients with Sweet syndrome. The median age of patients was 57.5 years old (range, 17–84), and 48.1% were female. Of the 52 patients analyzed, 27 patients (51.9%) had malignancy-associated Sweet syndrome. Sweet syndrome was diagnosed concurrently with (N = 8), before (N = 5), and after (N = 14) the diagnosis of malignancy. The idiopathic Sweet syndrome was most common in the non-malignancy group (56.0%). Myelodysplastic syndrome was the most common malignancy associated with Sweet syndrome (47.6%). Leukopenia (p = 0.005), anemia (p < 0.001), and thrombocytopenia (p = 0.008) were significantly associated with malignancy. The majority of patients showed rapid improvement of symptoms after steroid administration. The symptoms of some patients with malignancy did not improve with steroid alone; however, their symptoms often improved when steroids were combined with a treatment for the associated malignancy. Relapse and aggravation of Sweet syndrome were common in the malignancy group. Sweet syndrome showed a broad spectrum of clinical features related to various diseases. Sweet syndrome often occurred as a paraneoplastic feature. Therefore, active systemic evaluation is needed in the first diagnosis of Sweet syndrome without clear etiology.