Langerhans cell histiocytosis (LCH) is a rare idiopathic disease characterized by the clonal proliferation of Langerhans cells. LCH may appear as a single osteolytic lesion or can affect many body systems. Oral involvement may predate systemic manifestations or mimic infectious/inflammatory disorders. This case report involves a 3-year-old boy referred to the pediatric dentistry residency clinic at the University of Puerto Rico to evaluate possible periodontal disease on primary second lower molars. Examination revealed bilateral extra-oral swelling on the left and right side of the face obliterating the mandibular angles. The overlying skin was intact and symptomless. An intraoral examination showed localized swelling of the overlying mucosa from the lower primary right and left molars with some degree of mobility on both the right and left second primary molars. This case illustrates the need for pediatricians and pediatric dentists to be aware of LCH mimicking periodontal lesions.