[Osseous desmoid fibroma of the mandible. An unusual case in a 15-month-old infant].

The authors present a rare case, unique in the literature, of an osseous desmoid fibroma in which the histological diagnosis was made at the age of fifteen months. The signs were of a slight swelling with complete trismus of the mandible. After excision of the tumour, with a resultant defect in the superior ramus of the mandible, the trismus disappeared spontaneously after two weeks.