title: Neutrophil-rich subcutaneous fat necrosis of the newborn: A potential mimic of infection.
abstract: BACKGROUND
  The inflammatory infiltrate seen in biopsy specimens obtained from patients with subcutaneous fat necrosis of the newborn (SCFN) has classically been described as consisting mostly of histiocytes. However, we encountered patients with SCFN whose biopsy specimens revealed mostly neutrophils, prompting infection to be an initial consideration.
  
  
  OBJECTIVE
  We sought to describe cases of SCFN in which neutrophils formed the majority of the infiltrate at our institution and in the literature.
  
  
  METHODS
  We performed a retrospective analysis of patients with SCFN reported at our institution and a literature review of SCFN.
  
  
  RESULTS
  Thirteen cases of SCFN were identified at our institution. In 2 of 13 cases, neutrophils composed >75% of the inflammatory infiltrate, and both lesions were 1 day old. From the literature review, neutrophils were mentioned as a component of the infiltrate in 10 of 124 cases, but in none were neutrophils described as forming the majority of the infiltrate.
  
  
  CONCLUSIONS
  This study is limited by its retrospective nature and small sample size.
  
  
  CONCLUSIONS
  Neutrophils can comprise most of the inflammatory cells in patients with SCFN, especially early in the course of the disease. This variant of SCFN can be easily mistaken for infection.
authors.affiliation: Department of Dermatology, University of California, San Francisco, California.
authors.forename: Roberto R
authors.initials: RR
authors.lastname: Ricardo-Gonzalez
authors.affiliation: Department of Medicine, Kaiser Permanente Medical Center, Santa Clara, California.
authors.forename: James R
authors.initials: JR
authors.lastname: Lin
authors.affiliation: Department of Dermatology, University of California, San Francisco, California.
authors.forename: Erin F
authors.initials: EF
authors.lastname: Mathes
authors.affiliation: Department of Dermatology, University of California, San Francisco, California; Department of Pathology, University of California, San Francisco, California.
authors.forename: Timothy H
authors.initials: TH
authors.lastname: McCalmont
authors.affiliation: Department of Dermatology, University of California, San Francisco, California; Department of Pathology, University of California, San Francisco, California. Electronic address: Laura.Pincus@ucsf.edu.
authors.forename: Laura B
authors.initials: LB
authors.lastname: Pincus
mesh_terms: D001706:Biopsy; D003937:Diagnosis, Differential; D005218:Fat Necrosis / Q000150:complications / Q000175:diagnosis* / Q000473:pathology*; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D009504:Neutrophils; D015434:Panniculitis / Q000150:complications / Q000175:diagnosis* / Q000473:pathology*; D012189:Retrospective Studies; D012874:Skin Diseases, Infectious / Q000175:diagnosis*; D050151:Subcutaneous Fat / Q000473:pathology*
keywords: neutrophils; panniculitis; subcutaneous fat necrosis of the newborn