BACKGROUND: Langerhans-cell histiocytosis (LCH) is a group of rare disorders histologically characterized by the proliferation of Langerhans cells. Multiple organs and systems may be involved by the disease. Typically, there is bone involvement and, less frequently, lesions may be found in the lungs, liver, lymph nodes, skin, and mucosae. Oral soft tissue lesions without bone involvement are rare. METHODS: We report a case of a 23-year-old man with LCH detected by oral soft tissue, cutaneous, and lung lesions. RESULTS: Due to the oral lesion diagnosis, important procedures were performed, which determined the staging of the disease. CONCLUSION: Gingival lesions could be one of the first manifestations of LCH. The periodontist should recognize and detect this important pathology with oral involvement.