A buccal bifurcation cyst is a rare, inflammatory odontogenic cyst that develops in the furcation of the first lower molar, with an etiology that is not well understood. It occurs in children between 5 and 13 years of age, with complaints of discomfort and sensitivity in the vestibular region of the lower molars, with secretion. Histologically, it was covered by a stratified squamous epithelium and chronic inflammatory infiltrate. Our case is of a 7-year-old patient with melanoderma, who complained of discomfort in the vestibular region of the right first lower molar, accentuated during palpation. With the technique of occlusal radiography, a circumscribed, radiolucent well-delimited area, near the vestibular region was observed. With osteotomy and enucleation of the lesion, the patient returned without symptoms, and is in clinical and radiographic follow-up, due to the histological confirmation of an inflammatory cyst diagnosis.