Rib and sternal lesions in pediatric Langerhans Cell Histiocytosis

Background: Langerhans 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. Methods: A 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. Results: Eleven 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). Conclusion: Our 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.