This study aims to (1) clinically and radiographically characterize a series of unifocal (single-system singlesite) and multifocal (single-system multiple-site) langerhans cell histiocytosis (LCH) lesions in the vertebra and (2) determine the success and recurrence rates with different treatment modalities in a pediatric population at a tertiary children's hospital. Patients younger than 18 years old with a diagnosis of LCH before 1 June 2021 at our institution were reviewed. The inclusion criteria were a unifocal or multifocal vertebral lesion without systemic disease. Clinical presentations, lesion sites, radiographic findings, treatments, complications, recurrence rates, and length of follow-up were reviewed and recorded. Thirtynine patients had unifocal (36%) or multifocal (64%) vertebral lesions. 44% of patients had vertebral lesions only. The most common clinical presentation was neck or back pain (51%) and difficulty or inability to ambulate (15%). 70 vertebrae were involved in total; 59% cervical, 62% thoracic, 49% lumbar, and 10% sacral. 88% of multifocal patients underwent chemotherapy compared to 60% of unifocal patients. The recurrence rate in the entire cohort was 10%. The median length of follow-up was 5.2 years (0.6-16.8). Chemotherapy is often utilized as a treatment for vertebral LCH lesions regardless of unifocal or multifocal osseous presentation, with good outcomes and low recurrence rates. However other treatments such as observation only and steroid injections may be a better option with smaller and less widespread lesions due to side effects and length of treatment with chemotherapy. Determination of more invasive treatments including surgical excision or fixation will need to be considered on a case-by-case basis. Level of evidence: IV.

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BackgroundLangerhans cell histiocytosis (LCH) is a rare disorder characterized by proliferation and tissue infiltration of dendritic cells, most commonly occurring in children. Though it can occur in any organ, it often manifests as skeletal lesions with rib and sternal lesions being common. Due to its ubiquitous nature, LCH lesions can be located in various sites or anatomical systems, however, few studies have characterized and reviewed the eventual outcomes after treatment of isolated rib and sternal LCH lesions, especially in regards to treatment and long-term sequelae. We aimed to characterize unifocal and multifocal skeletal LCH lesions in the rib and sternum to determine the success and recurrence rates with different treatment modalities in a pediatric population at a tertiary children's hospital.MethodsA retrospective analysis found 11 patients younger than 18 years old with a diagnosis of unifocal or multifocal LCH lesions of the rib or sternum. Clinical presentations, lesion sites, additional skeletal lesions, biopsy site, radiographic findings, treatments, recurrence rates, and length of follow-up were reviewed and recorded. ResultsEleven patients were found to have unifocal or multifocal LCH lesions involving the rib or sternum (6 males and 5 females). The median age at diagnosis was 7.3 years (0.85-11.8). Three patients (27%) had their lesions resected surgically, all in unifocal cases. All patients had a lytic bone lesion on radiograph, with 3 (27%) pathological fractures. One patient had a local wide excision, one had intralesional curettage, and one patient did not have surgical methodology available. The only unifocal case that did not have a resection was treated with a steroid injection only. All other cases were multifocal and were treated with chemotherapy. There were two cases of recurrence, with both occurring in the multifocal group. Median length of follow-up was 3.4 years (0.36-13.1).ConclusionOur study found that surgical resection with intralesional corticosteroid injection is an appropriate option for unifocal rib and sternal LCH lesions, while rib lesions that are part of a multifocal presentation may be managed adequately with chemotherapy alone. Surgical curettage, resection with intralesional steroid therapy may also be adequate for single-system multifocal skeletal lesions that are anatomically accessible and small in number and size.