MRI and CT Features of an Equine Juvenile Mandibular Ossifying Fibroma

A 5-month-old draught horse foal was admitted for evaluation of a mass on the rostral mandible. On the left rostral mandible, a 13 × 6 × 4 cm mass was located on the rostral part of the mandible, projecting more to the left side. The foal showed no signs of pain upon palpation or manipulation of the mass. Radiographs demonstrated a well-marginated bony proliferation which had developed at the rostral extremity of the mandible, at the base of the incisor teeth. An equine juvenile mandibular ossifying fibroma (EJMOF) was diagnosed on the basis of clinical findings. The owner declined surgical treatment. Magnetic resonance imaging (MRI) and computed tomography (CT) were performed postmortem in order to describe the MRI and CT features of EJMOF. Histological findings confirmed the diagnosis. MRI and CT features of EJMOF examined in this case report are very similar to those reported in human cases. It seems that the limits of the lesion are better delineated on MRI and CT images than on classical plain radiographs. CT and MRI can enhance surgical planning in order to ascertain complete excision of the mass. More and more equine clinics are equipped with CT and MRI. No description of CT or MRI characteristics of an EJMOF are available in the literature.