Sir, we would like to present an interesting case of unusual extra-oral manifestation of mandibular exostosis. A 30-year-old woman presented to an outpatient clinic of the Department of Oral Surgery, Medical University of Warsaw, Poland because she was worried about the asymmetrical deformity of her face that had grown over one year. She was terrified because she was suspecting a cancer origin of the lesion. On examination the patient presented unilateral painless swelling at the right side of the lower part of the face (Fig. 1). Intraoral examination revealed the non-tender protrusion of the body of the mandible accompanied by the shallow oral vestibule below the lower right molars. All teeth in the affected quadrant were vital and didn't present any pathological symptoms. Radiographic examination (CBCT) revealed the presence of the buccal exostosis, a dense overgrowth of body of the mandible (indicated by arrows in Fig. 2). The treatment consisted of intraoral exposure of the deformity (indicated by arrows in Fig. 3) and complete excision of the extended bone under local anaesthesia. Histopathological examination confirmed benign overgrowth of the dense cortical bone with a low content of trabecular bone. No recurrence of the lesion was observed two years after surgery.

Figure 1
figure 1

Unilateral painless swelling on the right lower side of the face

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Figure 2
figure 2

Buccal exostosis revealed in the CBCT

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Figure 3
figure 3

Intraoral exposure of the deformity for complete excision of the extended bone

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Exostoses are protuberances of calcified bone which are designated according to typical anatomic location. Exostoses of the lingual side of the mandible and buccal side of the maxilla occur relatively often. Buccal mandibular exostoses occur very rarely, may have large dimensions and change the feature of the face. For that reason they might constitute a diagnostic challenge. They can, however, be surgically treated with no recurrence in long-term follow-up. Exostoses should always be differentiated from benign and malignant neoplastic processes by means of histopathological examination.