Intraosseous Myofibroma of the Mandible in a 7-Year-Old Patient: A Case Report

Myofibroma is a benign fibrous tumour that occurs predominantly in the head and neck region followed by the trunk and extremities. However, cases occurring in the oral cavity are rare, presenting with a variable clinical appearances and wide differential diagnosis.  We reported a case of a 7-year-old girl who was referred to the Department of Paediatric Dentistry, Tengku Ampuan Rahimah Hospital with a progressively enlarging painless swelling on the left posterior region of the mandible over the past 3 months.  The swelling was associated with ulceration and displaced lower left first permanent molar.  Radiographic investigations reported well-defined radiolucency at molar area, alveolar expansion and bone resorption of the left posterior alveolar ridge of the mandible. Complete surgical excision of the lesion was performed under general anaesthesia.  Histopathological examination revealed proliferation of spindle shaped cells with biphasic growth pattern. Immunohistochemical staining showed strong positivity with vimentin and smooth muscle actin whilst negative for desmin, S100 and CD34 establishing the diagnosis of myofibroma. Although rare, myofibroma should be considered as a differential diagnosis for solitary firm swelling in the oral cavity. Histopathological examination together with immunohistochemical analysis is essential for an accurate diagnosis.