title: Recurrent adult-onset hypophyseal Langerhans cell histiocytosis after radiotherapy: a case report.
abstract: BACKGROUND
  Langerhans cell histiocytosis is a rare disease within the adult population, with very few cases reported as solitary hypophyseal lesions in adults. Of the reported cases, most have been treated successfully with surgery, radiotherapy, and/or chemotherapy. Radiotherapy has been thought to be curative at the relatively low dose of 20Gy. Here we report a case of recurrent hypophyseal Langerhans cell histiocytosis 9 months after radiotherapy with an interval period of symptomatic and radiographic response to therapy.
  
  
  METHODS
  A 50-year-old Caucasian woman who had headaches, memory difficulties, and diabetes insipidus was found to have a 2.5cm suprasellar mass. Langerhans cell histiocytosis was diagnosed following stereotactic brain biopsy. Further workup revealed no other lesions. Initial radiation treatment succeeded in shrinking the tumor and relieving clinical symptoms temporarily; however, growth and recurrence of clinical symptoms was noted at 9 months. Re-irradiation was well tolerated and the patient had no acute side effects.
  
  
  CONCLUSIONS
  Isolated hypophyseal involvement by Langerhans cell histiocytosis in adults is a unique presentation of a rare disease. Although radiotherapy doses as low as 20Gy have been reported to offer control, this case demonstrates that higher doses may be warranted to ensure tumor control. With modern imaging and radiotherapy techniques higher doses should offer little increased more durable risk to surrounding critical structures.
authors.affiliation: Department of Radiation Oncology, Mallinckrodt Institute of Radiology and Siteman Cancer Center, Washington University Medical School, 4511 Forest Park Avenue, Saint Louis, MO, 63108, USA. jjaboin@radonc.wustl.edu.
authors.forename: Ryan K
authors.initials: RK
authors.lastname: Funk
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Ferraro
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Perrin
authors.forename: Kyle M
authors.initials: KM
authors.lastname: Hurth
authors.forename: John J
authors.initials: JJ
authors.lastname: Stephens
authors.forename: David B
authors.initials: DB
authors.lastname: Mansur
authors.forename: Michael R
authors.initials: MR
authors.lastname: Chicoine
authors.forename: Joseph R
authors.initials: JR
authors.lastname: Simpson
authors.forename: Jerry J
authors.initials: JJ
authors.lastname: Jaboin