RESUMEN
Solitary myofibroma is an uncommon benign soft tissue neoplasm of myofibroblastic origin exhibiting head and neck region predilection but its presence in the jaws is rare. Myofibroma presents as painless mass and may demonstrate rapid enlargement and growth that clinically mimic malignancies. This report presents a 4-year-old male patient with a rapidly growing mandibular gingival mass with some evidence of underlying alveolar bone destruction. Incisional biopsy was performed and the specimen was stained with hematoxylin and eosin and immunohistochemical antibodies for alpha SMA, CD34, S100 and desmin. The diagnosis of myofibroma was made and the lesion was completely excised. The knowledge about microscopic features of this rare neoplasm helps to have a proper diagnosis and avoid unnecessary treatment