Fibrodysplasia Ossificans Progressiva (FOP): A Case Report with Oral and Maxillofacial Manifestations and new radiographic feature

Fibrodysplasia ossificans progressiva (FOP) is a rare form of genetic disorder categorized by progressive heterotopic ossification and congenital deformity of the big toes. Heterotopic ossification follows gradual inflammation of the soft tissues (flare-up) and results in limited movements in joints such as the Temporomandibular joint (TMJ). No effective medical treatment has been recognized for the treatment of FOP. FOP is commonly misdiagnosed, especially in the maxillofacial region. Patients with FOP often experience temporomandibular joint ankylosis. Therefore, dental professionals should be careful in planning treatment, including avoiding anesthesia injections, especially in the mandible. This study presents a case of FOP with temporomandibular joint ankylosis. An eight-year-old boy with the chief complaint of reduced mouth opening and clinical and radiological features of FOP.  The patient was referred to Mashhad Dental School in January 2016. He had not previously been diagnosed with FOP.