Odontogenic myxoma of the mandible in a 5-year-old boy presenting with trismus: a case report

Odontogenic myxoma is a rare benign odontogenic tumour that is uncommon in young children and usually presents as a painless jaw swelling. We report a 5-year-old boy presenting with long-standing trismus. Orthopantomogram and MRI showed a multilocular radiolucent lesion of the left mandibular body and ramus with medial cortical perforation and close relation to the medial pterygoid muscle. Biopsy confirmed odontogenic myxoma. The lesion was treated with enucleation and curettage, preserving mandibular continuity but sacrificing the inferior alveolar nerve. At 1-year follow-up there was good radiographic bone regeneration and no evidence of recurrence; mouth opening remained severely limited despite physiotherapy and jaw-stretching exercises. This case illustrates paediatric odontogenic myxoma of the mandible presenting primarily with trismus and highlights the risk of persistent functional impairment even after successful tumour removal. Prolonged, progressive trismus in a child should be considered a red-flag symptom that warrants prompt imaging and specialist evaluation.