title: Langerhans cell histiocytosis of bone in children: a clinicopathologic study of 108 cases.
abstract: BACKGROUND
  Langerhans cell histiocytosis (LCH) is a rare disease that is characterized by abnormal proliferation of pathological Langerhans cells (LCs). In this study, a total of 108 pediatric patients with LCH of bone were evaluated retrospectively for illustrating the clinicopathologic features of this disease, with a goal of improving the diagnosis, treatment, and prognosis.
  
  
  METHODS
  A retrospective study was based on the clinical records and pathological data of 108 patients (13 days to 12 years of age) with LCH of bone from a single hospital. Hematoxylin-eosin stain and immunohistochemical stain were applied. The follow-up was conducted to June 2008.
  
  
  RESULTS
  The peak age of the patients ranged between 3 years and 6 years (80.6%, 87/108), and male gender predominated. The most common clinical presentation was local pain, and the imaging findings commonly showed an isolated lytic lesion in the bone. Of the 108 patients, 79 (73.1%) had single bone involvement, 27 (25.0%) had multi-bone involvement (with or without related skin involvement), and 2 (1.8%) had multisystem involvement. Histologically, all the lesions revealed abnormal proliferation of pathological Langerhans cells along with an admixture of eosinophils, lymphocytes, and other inflammatory cells. The LCs have similar shape and are positive for cluster of differentiation 1a (CD1a) (100.0%, 60/60), S100 (90.0%, 54/60), CD68 (41.7%, 25/60), lysozyme (Lys) (40.0%, 24/60), and macrophage antigen compound (MAC) 387 (30.0%, 18/60); cytokeratin (CK) and epithelial membrane antigen (EMA) were negative. The overall survival rate was 98.0% at a median follow-up of 5 years.
  
  
  CONCLUSIONS
  LCH of bone in children is predominant in males and usually shows as an isolated lytic lesion. Histologically, the lesions reveal abnormal proliferation of pathological Langerhans cells, admixed with various types of inflammatory cells. The patients have a good prognosis, except those with multi-system involvement.
authors.affiliation: Department of Pathology, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200092, China.
authors.forename: Jia
authors.initials: J
authors.lastname: Wang
authors.forename: Xv
authors.initials: X
authors.lastname: Wu
authors.forename: Zheng-Jun
authors.initials: ZJ
authors.lastname: Xi
mesh_terms: D001847:Bone Diseases / Q000473:pathology*; D002648:Child; D002675:Child, Preschool; D003952:Diagnostic Imaging; D005260:Female; D005500:Follow-Up Studies; D006646:Histiocytosis, Langerhans-Cell / Q000473:pathology* / Q000628:therapy; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D011379:Prognosis; D012189:Retrospective Studies; D015996:Survival Rate; D016896:Treatment Outcome