Introduction: Langerhans cell histiocytosis (LCH) is a rare inflammatory myeloid neoplasia of unknown etiology occurring in both children and adults. This condition is characterized by an abnormal proliferation of Langerhans cells that may virtually affect all sites in the human body. Oral manifestations of LCH could be the first clinical sign of disease and its periodontal localization could be easily mistaken for other more common entities, such as chronic periodontitis, aggressive periodontitis, and necrotizing ulcerative periodontitis. Case presentation: A 32-years old female visited a private dental practice with a chief complaint of sensitivity in the mandibular left first molar. Clinical and radiographic examination revealed deep periodontal pocket, recession, furcation involvement, mobility, severe alveolar bone destruction and a diagnosis of aggressive periodontitis was rendered. Multiple tooth extractions were carried out due to progressive periodontal destruction with impaired healing and development of ulcerative lesions. Multidisciplinary investigation demonstrated that the periodontal involvement was a manifestation of an underlying systemic disease. A biopsy of a bone lesion was therefore performed, revealing the presence of multifocal single system LCH. Conclusion: The identification of periodontal LCH is not trivial given that it may clinically resemble other periodontal disease entities. The dentist can be the first health care personnel to unravel the presence of an underlying systemic LCH.