Background
A lipoma is a benign tumor which may occur in the adipose tissue of any part of the body. The tumor is most commonly found on the trunk and extremities. Although it is the most common tumor of mesenchymal origin in the head and neck, its incidence is relatively rare. Lipoma of the head and neck is usually located in subcutaneous tissue. It is rarely deep seated with osseous involvement and rarely occurs in children, especially below the age of 10.
Material and Method
The case of a painless mass of one-year history in the right parotidomasseteric region of an eight-year-old boy is presented. The mass was revealed to be a classical lipoma in the masseteric space, possibly causing hyperostosis of the angle of the mandible. After removal of the mass and a spherical protuberance in the angle of the mandible, the boy recovered and no recurrence was noted after one-year follow-up.
Results

Conclusions
Hyperostosis is a rare phenomenon with lipoma. In this case, the hypothesis was posed that the tensile force produced by the lipoma in the masseteric space possibly caused hyperostosis of the angle of the mandible. To the authors' knowledge, a classical lipoma arising from the deep fascial space resulting in osseous change has not been described in the literature before.

Keywords: Mandible - pathology, Magnetic Resonance Imaging, Lipoma - pathology, Hyperostosis - pathology, Head and Neck Neoplasms - pathology, Child, Soft Tissue Neoplasms - pathology, Stress, Mechanical