{Reference Type}: Case Reports {Title}: A case report of adult Langerhans cell histiocytosis and review of the literature. {Author}: Lavaee F;Nazhvani AD;Afshari A; {Journal}: Clin Case Rep {Volume}: 11 {Issue}: 2 {Year}: Feb 2023 暂无{DOI}: 10.1002/ccr3.6927 {Abstract}: Langerhans cell histiocytosis (LCH) is an uncommon proliferative disease with an unknown cause. Its clinical manifestations vary and can involve a variety of organs. To diagnose LCH, radiographs, histopathological and immunohistochemical findings are essential. The gold standard for a definite diagnosis is positive CD1a/CD207 and S100 in the immunohistochemical results. Different treatment plans are available for patients struggling with LCH. To our knowledge, the LCH incidence rate is about 8.9 in one million children and 1-2 cases in one million adults. Our case shows the importance of early diagnosis of this rare condition for the prevention of any further spreading. This case report is about a 35-year-old male patient struggling with diabetes insipidus with a chief complaint of tooth mobility. Based on his X-ray radiographs, osteolytic lesions were found. A biopsy was performed, and due to histopathological and immunohistochemical findings, it was diagnosed as a case of LCH in adults. This paper shows that although the incidence rate of LCH is rare in adults, dealing with a patient struggling with diabetes insipidus and osteolytic bone lesions with an unknown cause, LCH must be taken into consideration. Due to the fact that LCH's first manifestations are mostly first oral, its good prognosis in the early stages, and if it progresses, it can turn fatal, it is important that dentists are aware of this disease, its clinical manifestations, and patient management. In case of suspicion, X-ray examination, biopsy, histopathological, and immunohistochemical exams must be performed.