Outcomes of Children Younger Than 24 Months With Langerhans Cell Histiocytosis and Bone Involvement: A Report From a Single Institution

BACKGROUND:Langerhans cell histiocytosis (LCH) is a rare disorder that ranges from single-system to disseminated multisystem disease. Patients younger than 24 months of age more commonly present with risk organ (liver, spleen, hematopoietic system, or lung) involvement at diagnosis and have a poor prognosis. Treatment approaches have changed over the last 25 years. Our goal was to describe the course and outcomes of patients younger than 24 months of age at diagnosis and identify the role of bone involvement in outcomes. METHODS:We conducted a retrospective chart review of patients diagnosed with LCH at Children’s Hospital Los Angeles from 1984 to 2010, focusing on 71 patients younger than 24 months of age at diagnosis. RESULTS:Ten patients had single bone lesions at diagnosis and did well irrespective of therapy. The majority of patients (40/71 or 56%) had multiple bone lesions. Of the 37 patients with multisystem disease, 27 children (73%) had risk organ involvement. Fourteen patients with risk organ involvement received ≤6 months of initial chemotherapy with prednisone and vinblastine. Six of these patients had reactivation of the disease, and bone was the most frequent site of reactivation. Seven patients with risk organ involvement were treated with at least 12 months of chemotherapy. Only one of these patients had reactivation of the disease, and none died. The majority (7/10) of patients with risk organ involvement who progressed on therapy died despite multiple treatment regimens. CONCLUSIONS:Patients younger than 24 months of age at diagnosis are more likely to have multiple bone lesions than older patients, supporting that a radiographic skeletal survey at the time of LCH diagnosis is important to evaluate the extent of bone involvement. Bones were the most common site for reactivation for all patients. As expected, subjects with risk organ involvement had better outcomes when treated with systemic chemotherapy for at least 1 year. LEVEL OF EVIDENCE:As a retrospective review of all cases at our institution over a 26-year period, this article represents level IV evidence.