title: Association of Langerhans cell histiocytosis with malignant neoplasms.
abstract: BACKGROUND
  The association of Langerhans cell histiocytosis (LCH) with a malignant neoplasm is rare and generally has been the subject of isolated case reports.
  
  
  METHODS
  A recent case of LCH seen at the University of Minnesota in combination with acute lymphoblastic leukemia led the authors to review their own charts from 1960 onward, in addition to the literature for other reported associations of LCH and malignant neoplasms.
  
  
  RESULTS
  In addition to the presented case and 3 cases from the files of the authors, the literature contained 87 reported cases. Of the 91 patients, 39 had LCH with malignant lymphoma (ML); 25 of these cases were Hodgkin disease. In 11 of these 39 patients, the LCH was diagnosed from 12 months to 33 years after the ML was diagnosed. In 62% of the patients with LCH-ML (24 patients), the diagnosis was made concurrently and the Langerhans cells were found in the same lymph nodes. In the remaining four patients, the diagnosis of LCH preceded that of ML by 6-24 months. In 22 patients, including 2 patients in the files of the authors, LCH was reported in association with leukemia; 16 (73%) of these cases were associated with acute nonlymphoblastic leukemia. In two cases the leukemia preceded the LCH. In 6 patients both diagnoses were made concurrently, and in 14 patients (64%) the diagnosis of LCH preceded the diagnosis of leukemia by 8 months to 17 years. In the remaining 30 patients, LCH was associated with a variety of solid tumors, including a lung carcinoma in 12 patients. In all of these 12 cases the LCH was confined to the lung, and in 75% (9 of 12) of patients the diagnoses were made concurrently. In the 16 patients in whom the LCH preceded the solid tumor, the malignant diseases in 69% (11 of 16) developed within the radiation field used for the treatment of the LCH.
  
  
  CONCLUSIONS
  The intimate and simultaneous association of LCH with ML and lung carcinomas suggests strongly that the process that leads to the association is a reactive one. However, in the patients with leukemia and the other solid tumors, the latency of the malignant neoplasm after the diagnosis of LCH is suggestive of a therapy-related process.
authors.affiliation: Department of Pediatrics, University of Minnesota School of Medicine, Minneapolis 55455.
authors.forename: R M
authors.initials: RM
authors.lastname: Egeler
authors.forename: J P
authors.initials: JP
authors.lastname: Neglia
authors.forename: D M
authors.initials: DM
authors.lastname: Puccetti
authors.forename: C A
authors.initials: CA
authors.lastname: Brennan
authors.forename: M E
authors.initials: ME
authors.lastname: Nesbit
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002675:Child, Preschool; D005260:Female; D006646:Histiocytosis, Langerhans-Cell / Q000150:complications*; D006689:Hodgkin Disease / Q000150:complications; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000150:complications*; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000150:complications