Langerhans cell histiocytosis (LCH) is a rare disease that arises from an abnormal increase in histiocytes. Due to its rare occurrence, the diagnosis of LCH is often delayed or missed. This report presents a case of LCH in a 16-month-old girl. After biopsy, the patient’s previous medical records were obtained. The records described the presence of a yellowish plaque on the forehead since birth, a characteristic feature of LCH. Earlier knowledge of this medical history would have helped facilitate the diagnosis of LCH. This report aims to inform clinicians of the clinical and histopathological features of LCH in order to aid in the early diagnosis of this disease, which can occur in infancy.

Langerhans cell histiocytosis (LCH) is a rare clinicopathologic disorder characterized by proliferation of histiocyte- like cells (langerhans cell histiocytes) accompanied by varying other inflammatory cells. LCH commonly involves the oral and maxillofacial region, but is very rarely seen. Then LCH has made it difficult to investigate the clinical and histological aspects. We investigated LCH of oral and maxillofacial region and analyzed clinical and histological characteristics. We reviewed the records of all patients who were diagnosed as LCH, retrospectively. Data included patient’s age, sex, chief complaint, clinical diagnoses, radiologic and histologic reports, and clinical course. We analyzed clinical and histological characteristics. From 2000 to 2007, 8 patients were diagnosed as LCH. 7 were children and 1 was adult. All cases involved mandible. Clinical type of all cases were“eosinophilic granuloma”. 6 cases were classified as“unifocal disease”and 2 cases were“multifocal single system diseases”. Microscopic findings commonly showed numerous histiocytes with eosinophilic cytoplasm (langerhans histiocytes). In 6 cases, immunohistochemical study was accomplished and confirmed the diagnosis of LCH. 6 cases were cured and not recurred, and 2 cases had loss of follow- up. Unifocal disease type of LCH may arise in Korean people more frequently than in western people (75% Vs 49%). Therefore, the higher frequency of unifocal disease of LCH is expected to raise the cure rate and to improve patient prognosis in Korean patients with LCH.