title: Sweet's syndrome: a spectrum of unusual clinical presentations and associations.
abstract: BACKGROUND
  Sweet's syndrome (SS) is the prototypic neutrophilic dermatosis. First described in 1964, the characterization of new clinical associations, unique histopathological findings and clinical variants have stimulated much interest and discussion recently. However, the prevalence of these unusual variants and clinical associations within a single cohort of patients, has not been described.
  
  
  OBJECTIVE
  To describe and evaluate the prevalence of unusual clinical and histopathological features, as well as the clinical associations of SS seen in patients from the National Skin Centre, Singapore.
  
  
  METHODS
  This is a retrospective study of all consecutive cases of SS seen at our centre over a 5.5-year period (June 1999-December 2004). Data on associated systemic diseases was obtained from the medical records and matched with information from the National Cancer Registry, Singapore. Patients not actively followed up for more than 3 months were contacted for their updated health status.
  
  
  RESULTS
  Thirty-seven patients were identified. Ten (27%) had non-idiopathic SS. These were associated with haematological disorders, connective tissue disorders, infections or a drug. Twenty-nine patients (78%) had at least one atypical clinical or histopathological feature. Atypical clinical features included bullous lesions, SS with hand involvement or neutrophilic dermatoses of the hands and the concomitant existence of subcutaneous SS with pyoderma gangrenosum. SS was the presenting feature in three patients with infections caused by atypical organisms, including Mycobacterium chelonae, Penicillium species and Salmonella type D. Unique histopathological variants included subcutaneous SS and lesions containing an admixture of mature and immature neutrophils. Subcutaneous neutrophilic inflammation seemed to be more common in patients with an underlying haematological disorder. This group of patients also had a lower mean haemoglobin level.
  
  
  CONCLUSIONS
  Unusual clinical and histopathological variants of SS described in the literature are similarly encountered in our cohort of patients, with some features being more common than others. We highlight and discuss some unique clinical and histopathological observations seen in our patients with SS.
authors.affiliation: National Skin Centre, 1 Mandalay Road, Singapore, Singapore. cyneoh@nsc.gov.sg
authors.forename: C Y
authors.initials: CY
authors.lastname: Neoh
authors.forename: A W H
authors.initials: AW
authors.lastname: Tan
authors.forename: S K
authors.initials: SK
authors.lastname: Ng
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000970:Antineoplastic Agents / Q000009:adverse effects; D001549:Benzamides; D003875:Drug Eruptions / Q000175:diagnosis / Q000473:pathology; D005260:Female; D006229:Hand Dermatoses / Q000175:diagnosis / Q000473:pathology; D019337:Hematologic Neoplasms / Q000150:complications; D006801:Humans; D000068877:Imatinib Mesylate; D008297:Male; D008875:Middle Aged; D009504:Neutrophils / Q000473:pathology; D010879:Piperazines / Q000009:adverse effects; D011743:Pyrimidines / Q000009:adverse effects; D012189:Retrospective Studies; D012872:Skin Diseases, Vesiculobullous / Q000175:diagnosis / Q000473:pathology; D016463:Sweet Syndrome / Q000175:diagnosis* / Q000209:etiology / Q000473:pathology
chemical_list: D000970:Antineoplastic Agents; D001549:Benzamides; D010879:Piperazines; D011743:Pyrimidines; D000068877:Imatinib Mesylate