Radiation Oncology/Histiocytosis

Langerhans' Cell Histiocytosis (LCH)

Overview

• Uncontrolled clonal proliferatoin of Langerhans' cells; arguments appear ongoing on whether this is a reactive or neoplastic process
• Incidence in US is ~1200 new cases/year
• Older name as Histiocytosis X; histocytic disorders are now divided into 3 groups: (1) dendritic cell histiocytosis, (2) erythrophagocytic macrophage disorders, and (3) malignant histiocytosis. LCH belongs to Group (1)
• Majority occur in children <15 years old, although adult cases are well documented
• Disease extent:
  • Clinical spectrum ranges from solitary, indolent lesions of bone (sometimes called eosinophilic granulomas) to an acute, fulminant disseminated disease (also called Letterrer-Siwe disease)
  • "Single-system disease" - involves one organ (e.g. bones, soft tissue, lymph nodes, etc.). Either single location (unifocal) or multiple sites may be affected
  • "Multi-system disease" - involves multiple organ systems
• Lytic bony involvement is common (~60%), either as single system disease or as part of multi-system disease process
• In children, the pituitary stalk is often involved (~50%), sometimes leading to diabetes insipidus (the triad of diabetes insipidus, proptosis, and lytic bone lesions is known as Hand-Schuller-Christian triad)
• Most patients with single-system disease never develop other LCH manifestations
• Conversely, patients with multi-system disease tend to have worse prognosis, with disease course driven by extra-osseous manifestations
• Unifocal bony lesions may resolve spontaneously, but early surgical or RT intervention is favored. Steroids can also lead to a local remission
• The role of RT is not well defined; typical indications include potential threat in case of disease progression (i.e. spinal cord compression), painful lesions not well controlled with surgery, sites where surgery would result in significant morbidity, or local relapse.
• There is a wide range of RT doses reported, both single dose (0.5 - 6 Gy) and fractionated (5 - 50 Gy). PMID 16447013 recommends total dose for bony disease in children 6/3 - 10/5 Gy and in adults 20/10 Gy
• For osseous lesions, a meta-analysis reports high local control (>90%)
• Multi-system disease may require chemotherapy
• Treatment guidelines for adults and children are available from Euro Histio Net http://www.eurohistio.net/e1623/e1554/index_eng.html

• Essen; 2006 (Germany) PMID 16447013 -- "Radiotherapy for bony manifestations of Langerhans cell histiocytosis. Review and proposal for an international registry." (Olschwski T, Strahlenther Onkol. 2006 Feb;182(2):72-9.)
  • Literature review. 65 studies, 698 patients with osseuous single-system disease and 348 patients with bony involvement of multi-system disease treated by RT
  • Outcome: single-system LC 96%, CR 93%; multi-system LC 92%, CR 76%
  • Conclusion: RT can be successful as a single treatment or in combination, with high remission and local control rates

Other links

• German LCH Registry Website and Registry RT Questionnaire