title: Clinicopathologic, Immunohistochemical, and Molecular Features of Histiocytoid Sweet Syndrome.
abstract: Histiocytoid Sweet syndrome is a rare histopathologic variant of Sweet syndrome. The nature of the histiocytoid infiltrate has generated considerable controversy in the literature.
  
  
  
  The main goal of this study was to conduct a comprehensive overview of the immunohistochemical phenotype of the infiltrate in histiocytoid Sweet syndrome. We also analyze whether this variant of Sweet syndrome is more frequently associated with hematologic malignancies than classic Sweet syndrome.
  
  
  
  This is a retrospective case series study of the clinicopathologic, immunohistochemical, and molecular features of 33 patients with a clinicopathologic diagnosis of histiocytoid Sweet syndrome was conducted in the dermatology departments of 5 university hospitals and a private laboratory of dermatopathology.
  
  
  
  The clinical, histopathological, immunohistochemical, and follow-up features of 33 patients with histiocytoid Sweet syndrome were analyzed. In some cases, cytogenetic studies of the dermal infiltrate were also performed. We compare our findings with those of the literature.
  
  
  
  The dermal infiltrate from the 33 study patients (20 female; median age, 49 years; age range, 5-93 years; and 13 male; median age, 42 years; age range, 4-76 years) was mainly composed of myeloperoxidase-positive immature myelomonocytic cells with histiocytoid morphology. No cytogenetic anomalies were found in the infiltrate except in 1 case in which neoplastic cells of chronic myelogenous leukemia were intermingled with the cells of histiocytoid Sweet syndrome. Authentic histiocytes were also found in most cases, with a mature immunoprofile, but they appeared to be a minor component of the infiltrate. Histiocytoid Sweet syndrome was not more frequently related with hematologic malignancies than classic neutrophilic Sweet syndrome.
  
  
  
  The dermal infiltrate of cutaneous lesions of histiocytoid Sweet syndrome is composed mostly of immature cells of myeloid lineage. This infiltrate should not be interpreted as leukemia cutis.
authors.affiliation: Departments of Dermatology and Pathology, Fundación Jiménez Díaz, Universidad Autónoma, Madrid, Spain.
authors.forename: Victoria
authors.initials: V
authors.lastname: Alegría-Landa
authors.affiliation: Departments of Dermatology and Pathology, Fundación Jiménez Díaz, Universidad Autónoma, Madrid, Spain.
authors.forename: Socorro María
authors.initials: SM
authors.lastname: Rodríguez-Pinilla
authors.affiliation: Department of Dermatology, Hospital Clínico Universitario, Salamanca, Spain.
authors.forename: Angel
authors.initials: A
authors.lastname: Santos-Briz
authors.affiliation: Department of Pathology, Hospital Universitario 12 de Octubre, Madrid, Spain.
authors.forename: José Luis
authors.initials: JL
authors.lastname: Rodríguez-Peralto
authors.affiliation: Department of Dermatology, Hospital General, Valencia, Spain.
authors.forename: Victor
authors.initials: V
authors.lastname: Alegre
authors.affiliation: Department of Dermatology, Medical University of Graz, Graz, Austria.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Cerroni
authors.affiliation: Dermatopathologie Laboratory, Friedrichshafen, Germany.
authors.forename: Heinz
authors.initials: H
authors.lastname: Kutzner
authors.affiliation: Departments of Dermatology and Pathology, Fundación Jiménez Díaz, Universidad Autónoma, Madrid, Spain.
authors.forename: Luis
authors.initials: L
authors.lastname: Requena
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D005260:Female; D005500:Follow-Up Studies; D006644:Histiocytes / Q000473:pathology*; D006785:Hospitals, University; D006801:Humans; D007150:Immunohistochemistry; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000175:diagnosis / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D016463:Sweet Syndrome / Q000150:complications / Q000473:pathology*; D055815:Young Adult