Atlantoaxial Langerhans cell histiocytosis radiographic characteristics and corresponding prognosis analysis

BACKGROUND: Langerhans cell histiocytosis (LCH) may affect atlas and axis, and there were very few published cases describing a characteristic of LCH of atlantoaxial. OBJECTIVE: The objective of the study is to investigate the image manifestations of atlantoaxial LCH to improve the in-depth comprehension on it. MATERIALS AND METHODS: A retrospective study was done of computed tomography (CT) and magnetic resonance imaging in atlas and axis and prognosis was analyzed. RESULTS: The study included 41 patients (average age 12.9 years and median age 8 years) diagnosed with LCH, with 75.6% under 15 years old. Eighty-four lesions of LCH were identified including 47 in the atlas and 37 in the axis. The osteolytic bone destructions in the atlas and axis were characterized, 22% accompanied by sclerotic margins. Thirteen patients had a compression fracture, 11 in the lateral mass of the atlas and 2 in the C2 vertebral body. Sixteen and three patients had atlantoaxial malalignment and dislocation, respectively. On T2-weighted images, 68.9% showed iso- or low-signal intensity, 27.6% showed hyperintensity signal, and 3.4% showed heterogeneous signal. On postcontrast images, 81.9% showed significant enhancement, 12.5% showed moderate enhancement, and 6.3% showed mild enhancement. CT reexamination of 14 patients indicated atlantoaxial bone destruction relatively repaired in 12 patients. Thirty-three patients were a follow-up, 81.8% had no significant symptoms and 18.2% with remaining symptoms. CONCLUSIONS: The atlas and axis were affected by LCH, mainly in children. The lateral mass was easily affected and compressed, destruction of the atlas and axis could lead to atlantoaxial joint instability. The prognosis was good in most of the patients.