Author:Dr. Divya puri Patient ms mary a eight year old female patient a resident of Kenya, presented to us with swellings in various parts of the body, stiffness in moving the neck and shoulders. The patient was relatively asymptomatic before one year when she developed swelling in the soft tissue overlying the upper chest and back. This was localised, tender, warm and non fluctuant. As the area healed there was progressive tightening of the skin overlying the involved area, with development of bony tissue, and bony swelling, with decreased range of movement in that area.

Over the course of a year, areas which became inflamed spontaneously or as a result of trauma or iatrogenic were replaced by thickened skin and heterotopic bone.The areas which were affected were the base of the skull, spine, shoulders, scapulae and chest. The area on the chest which had been biopsied developed ossification.There was gradually difficulty in moving the neck, raising the shoulders above horizontal level. She was diagnosed as fibrodysplasia ossificans progressiva, clinically and on the basis of her X rays and bone scintigraphy. This disease is a rare autosomal dominant disorder because of recurrent mutation in ACVR1/ALK2, a bone morphogenetic protein (BMP) type 1 receptor. This may be one of the most highly specific disease causing mutation in the human genome.Characteristics of diagnostic value are hallux valgus deformity, joint immobilization (due to periarticular ossificans) and a thoracic deformity.Our patient had typical bony swellings at areas of previous trauma, she also had heterotopic bone formation at the area where muscle biopsy was performed.

She had osteochondroma arising from the medial distal metaphysis of femur. She had multiple heterotopic calcifications and ankylosis of the cervical spine. Bone scan revealed focal areas of increased tracer uptake in right external occipital protruberence of the skull extending along the paraspinal muscles upto right suprascapular region, right paraspinal muscles in the lower thoracic and lumbar regions, intercostal muscles in the region of left fourth and fifth ribs and right fourth to seventh ribs. All these areas likely represent heterotopic bone.Proximal tibial osteochondromas are a common phenotypic feature. Mobility of the spine may be restricted due to ankylosis of the spine and the rib cage.

Imaging reveals abnormally shaped long bones with exostoses and developmental fusion of cervical vertebrae. Bone scintigraphy shows an increased uptake of radiolabelled tracer in the affected areas.No effective medical management is available. Bisphosphonates and steroids are beneficial during flares. Gene therapy may hold promise.