Fibrodysplasia ossificans progressiva

Kevin Boyd, DO

Midwestern University

Richard M. Shore, MD

Children's Memorial Hospital

Abstract

1 yr old with painful neck masses

Keywords

Fibrodyslpasia ossificans progressiva 1499 FOP, myositis ossificans progressiva SPR unknown #8

Publication Date: 2009-01-30

History

1 yr old previously healthy, full term female presents to PCP with subcutaneous masses along neck and back which are intermittently painful. Pt eventually hospitalized for evaluation of enlarging soft tissue mass along her posterior neck.

Patient returned 3 months later with gait disturbance and new tender scalp nodules. A CT of the head was performed.

Findings

MRI (images 1-3): T1, T2 and post gad demonstrate abnormal increased T2 signal and enhancement within the trapezius muscles bilaterally

CT of the head (images 4-6): performed 3 months later. Shows interval ossification within the trapezius muscles. Multiple small, soft tissue nodules within the scalp.

Plain films performed subsequently (images 7-10): Ossification within the posterior neck and along the proximal left thigh. Abnormal appearance of the great toes bilaterally with hallux valgus deformity and abnormally small proximal phalanges, possibly fused to the metatarsals.

Diagnosis

Fibrodysplasia ossificans progressiva

DDx

In early stages, FOP may mimic tumors of soft tissue.

Exostosis-like projections may be attributed to multiple exostoses, traumatic myositis ossificans, Klippel-Feil syndrome or juvenile rheumatoid arthritis.

Discussion

Fibrodysplasia ossificans progressiva

One of the rarest, most disabling genetic conditions known to medicine, it causes bone to form in muscles, tendons, ligaments and other connective tissues. Bridges of extra bone develop across joints, progressively restricting movement and forming a second skeleton that imprisons the body in bone. This disorder is related to increased bone morphogenetic protein (BMP)signaling due to an activating mutation of a specific BMP receptor.

Major clinical findings:

Short

great toe with hallux valgus present at birth.

Tender soft tissue lumps on trunk or extremities.
Progressive stiffness of neck, back and decreased mobility.
Occasional baldness and deafness.

Major radiological features:

Short

great toe with a short proximal phalanx that may be fused with the first metatarsal. Lateral deviation at the interphalangeal joint.

Exostosis-like bony projections at ligamentous instertions near joint.
Ossification along the paraspinal ligaments.
Soft tissue

ossification.

Progressive fusion across apophyseal joints.

Course and prognosis:

Great toe findings evident at birth and symptoms usually begin in infancy
80% have some form of restrictive

ossification by 7 yrs.

Progressive ossification leads to eventual to permanent immobility with possible respiratory compromise.
Trauma and biopsy increase ossification.

References

Spranger, JW; Brill, PW; Poznanski, A. Bone Dysplasias An Atlas of Genetic Disorders of Skeletal Development. New York: Oxford University Press; 2002.
International FOP Association, Inc., www.ifopa.org

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