AbstractLangerhans cell histiocytosis (LCH) is a rare idiopathic disorder that results in tissue destruction due to the intense and abnormal proliferation of histiocytes. It affects numerous organs, but isolated mandibular osteolysis has not been previously reported as an initial manifestation of this disease. This paper aims to describe an unusual presentation of LCH in the mandible of a 10-year-old girl initially assessed to have Gorham’s disease based on clinical and imaging findings. Computerized tomography (CT) scan and MRI showed extensive lysis and resorption of the mandible, with note of a contrast-enhancing soft-tissue mass in the right maxillary sinus. Incisional biopsy and histopathologic examination were performed, and the diagnosis of LCH was established and confirmed by S100 and CD1-a immunostaining positivity. The patient underwent chemotherapy with vinblastine and prednisone which eventually resulted in reconstitution of the patient’s mandible. LCH should be considered as a differential in...