Fibrodysplasia ossificans progressiva: a current review of imaging findings

Abstract

Recognition of the imaging manifestations of fibrodysplasia ossificans progressiva is imperative to early diagnosis in order to appropriately direct patient care and preclude unnecessary biopsies or surgical procedures.

Bilateral fibrodysplasia ossificans affecting the masticatory muscles and causing irreversible trismus in a domestic shorthair cat

“…8–16 Cardiorespiratory failure, secondary to increased pulmonary vascular resistance, is the most common cause of death in human patients, 18 usually occurring during the second to fifth decades of life. 1,2 Involvement of the oromaxillofacial region is an additional concern, as it may compromise vital primary requirements, such as air and food intake.…”

“…In humans, the most important imaging feature of FOP is the late ectopic ossification of soft tissue that is easily seen with CT. 2,22,23 Non-mineralised early-to-intermediate - stage FOP lesions are oedematous, markedly inflammatory and progressively fibroproliferative. With CT, such lesions may appear as swelling of the facial plane around muscles that is isodense to hypodense with a variable enhancement pattern, depending on the balance between inflammation and neovascularity.…”

“…1,2 It results in dysregulation of the bone morphogenic protein (BMP) pathways within the connective tissues. 1,2 Pathophysiology of the disease starts with minor soft-tissue injuries that trigger an inflammatory response leading to muscle injury and necrosis, and subsequent fibroproliferation, maturing to endochondral bone formation. Regional swelling and great toe malformation of (bilateral hallux valgus) are also usually present in people.…”

“…Regional swelling and great toe malformation of (bilateral hallux valgus) are also usually present in people. 1,2 Maxillofacial presentations affecting the masticatory muscles alone or together with extra-skeletal lesions elsewhere in the patient, resulting in unresolving trismus, have been reported in humans. 3–7 No medical or surgical treatment has yet been proven to give any prophylactic or curative effect.…”

Special considerations for clinical trials in fibrodysplasia ossificans progressiva (FOP)

“…Children who have FOP appear normal at birth except for congenital malformations of the great toes. Radiological findings can assist with diagnosis of the disease . During the first decade of life, sporadic episodes of painful soft tissue swellings (ʻflare‐upsʼ) occur spontaneously or can be precipitated by soft tissue injury, intramuscular injections, viral infection, muscular stretching, muscular fatigue or falls.…”