title: Combined Erdheim-Chester disease and Langerhans cell histiocytosis of skin are both monoclonal: a rare case with human androgen-receptor gene analysis.
abstract: BACKGROUND
  Erdheim-Chester disease (ECD) is a rare xanthogranulomatous histiocytic disorder. Langerhans cell histiocytosis (LCH) is a proliferative disorder of histiocytes with a phenotype similar to dendritic Langerhans cells. Both are derived from myeloid stem cells in the bone marrow and, thus, can overlap.
  
  
  OBJECTIVE
  We report a rare case of hybrid LCH and ECD of the skin with systemic ECD.
  
  
  METHODS
  Pathologic examinations and human androgen-receptor gene assay were used to study this case.
  
  
  RESULTS
  A 34-year-old woman presented with recurrent ulcerative skin lesions on both thighs associated with polydipsia and polyuria since childhood. Radiography revealed osteosclerosis of bilateral distal tibias and soft tissue masses of bilateral chest walls and ankles. Pathologically, the chest wall lesions showed dense aggregates of lipid-laden histiocytes, which were CD68(+)/CD163(+)/S100(-)/CD1a(-). Combined with the clinical and radiographic findings, this xanthogranulomatous infiltrate was consistent with ECD. However, thigh skin showed discrete foci of a xanthogranulomatous infiltrate and S100(+)/CD1a(+) Langerhans cells with eosinophils. In addition, Birbeck granules were found. Dissected tissues from both ECD and LCH were monoclonal, supporting their neoplastic nature.
  
  
  CONCLUSIONS
  Single case report is a limitation.
  
  
  CONCLUSIONS
  ECD and LCH may have a close association with divergent differentiation from the same stem cells under different microenvironmental conditions.
authors.affiliation: Department of Anatomic Pathology, E-Da Hospital, Kaohsiung County, Taiwan.
authors.forename: Jen-Wei
authors.initials: JW
authors.lastname: Tsai
authors.forename: Jen-Hui
authors.initials: JH
authors.lastname: Tsou
authors.forename: Liang-Yi
authors.initials: LY
authors.lastname: Hung
authors.forename: Hung-Bo
authors.initials: HB
authors.lastname: Wu
authors.forename: Kung-Chao
authors.initials: KC
authors.lastname: Chang
mesh_terms: D000328:Adult; D031249:Erdheim-Chester Disease / Q000150:complications* / Q000000981:diagnostic imaging / Q000235:genetics*; D005260:Female; D006646:Histiocytosis, Langerhans-Cell / Q000150:complications* / Q000235:genetics* / Q000473:pathology; D006801:Humans; D010026:Osteosclerosis / Q000000981:diagnostic imaging / Q000209:etiology / Q000235:genetics; D010641:Phenotype; D011859:Radiography; D011944:Receptors, Androgen / Q000235:genetics*; D012867:Skin / Q000473:pathology; D012883:Skin Ulcer / Q000209:etiology / Q000235:genetics / Q000473:pathology
chemical_list: D011944:Receptors, Androgen