Pre- and post-therapy MR imaging in fibrodysplasia ossificans progressiva.

Fibrodysplasia ossificans progressiva, also known as myositis ossificans progressiva, is characterized by congenital skeletal malformations and progressive ectopic bone formation in connective tissues. The disorder presents as rapidly growing masses usually in the neck or paraspinal region with stiffness in the adjoining joints. The preosseous lesions involve the fascia, ligaments, tendons, and skeletal muscle. These lesions occasionally resolve but more often progress to form ectopic ossification. We present a boy who had a characteristic clinical presentation. Magnetic resonance (MR) imaging conducted in the preosseous stage of the lesion revealed the pathology, resulting in early therapy and resolution of the preosseous lesion without progression to ossification. To the best of our knowledge, post-therapy follow-up MR imaging in such a case has not been reported.