Vertebral or femoral bone lesions at risk for collapse
A single vertebral body lesion without soft tissue extension to the extradural space may be observed only.
Low-dose radiation therapy may be used to try to promote resolution in an isolated vertebral body lesion or a large femoral neck lesion at risk for fracture, where chemotherapy is not usually indicated (single bone lesion). Despite the low dose required (700–1,000 cGy), radiation therapy should be used with caution in the area of the thyroid gland, brain, or any growth plates.
Patients with soft tissue extension from vertebral lesions are often treated successfully with chemotherapy,[Level of evidence: 3iiDiii] but prolonged therapy does not appear to be needed beyond the period required to reduce the mass and any risk to the spinal cord. The risk of reactivation of a single bone lesion was only 9% in one large retrospective series.
When instability of the cervical vertebrae and/or neurologic symptoms are present, bracing, or rarely, spinal fusion may be needed. Patients with soft tissue extension from the vertebral lesions are often treated successfully with chemotherapy.[Level of evidence: 3iiDiii]
Multiple bone lesions (single-system multifocal bone)
The most commonly used systemic chemotherapy regimen is the combination of vinblastine and prednisone. Based on the results of the HISTSOC-LCH-III trial, 12 months of treatment with weekly vinblastine (6 mg/m2) for 7 weeks then every 3 weeks is used for good responders. Prednisone (40 mg/m2) is given daily for 4 weeks then tapered over 2 weeks. Afterwards prednisone is given for 5 days at 40 mg/m2 every 3 weeks with the vinblastine injections. A short (<6 months) treatment course with only a single agent (e.g., prednisone) is not sufficient, and the number of relapses is higher. A reactivation rate of 18% was reported with a multidrug treatment regimen that was used for 6 months versus a historical reactivation rate of 50% to 80% with surgery alone or with a single-drug treatment regimen.