Fibrodysplasia ossificans progressiva (FOP): report of a case with extra-articular ankylosis of the mandible.

Fibrodysplasia ossificans progressiva (FOP) is a rare hereditary disorder of skeletal malformations and progressive heterotopic ossification. The worldwide prevalence is estimated to be one in 2 million. This report outlines the management of a patient with FOP limited to the maxillofacial region where the FOP lesion produced a fusion between the mandibular ramus and the zygomatic complex and trismus. The patient underwent three surgical procedures and various medical treatments during a 19-year period in attempts to manage the trismus, all in vain. The initial difficulty in establishing the diagnosis and ignorance of the true nature of the disease led to unsuccessful surgery.