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| Discussion |
Case Report:
A 8-year-old boy presented with multiple bony hard swellings over the para spinal region, gradually increasing in size over a two year period with progressive limitation of movements. At present, the child is barely able to flex and can minimally rotate his head.
The child was born out of non consanguineous marriage, full term normal delivery with no ante, intra or postnatal complications. Family history was not significant.
His symptoms started around two years ago, when he developed swellings over the para spinal region which were soft in consistency. There was no associated pain or fever. He was investigated with multiple x rays.
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Fig. 1 |
Fig. 2 |
The radiographs revealed no abnormality except for congenital fusion of C 4-5-6 vertebrae. The swelling subsided on its own.
About eight months ago, he developed a similar swelling in the same region. To investigate this swelling, an MRI of the spine spine and biopsy was done.
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MR spine revealed extensive T 2 hyperintense signal in bilateral para spinal muscles (edema) without any spinal abnormality suggesting myositis.
Biopsy of the para spinal muscles revealed inflammatory changes in the muscle with minimal fibrosis. Impression was Inflammatory Myositis vs Duchene muscular dystrophy.
The child progressively worsened with increasing limitation of movements of the cervical and lumbar regions and was referred to our institution for further management.
On physical examination, multiple bony hard swellings about 4-6 cms in diameter were noted in the cervical and dorsolumbar region. The lesions were fixed. There was no tenderness, warmth, redness or any evidence of inflammation. The patient had no other bony abnormality except for hallux valgus. The range of movement at the cervical and dorso lumbar spine was severely restricted.
CURRENT INVESTIGATIONS:
Radiographs of the cervical and dorso lumbar spine were taken.
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Fig. 5 |
Lateral radiograph of the cervical spine reveals congenital fusion of C 4-5-6 vertebrae with decreased intervertebral space. There is linear sheet like calcification seen just beneath the subcutaneous plane extending inferiorly from the sub occipital region.
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Fig. 6 |
Lateral radiograph of the dorso lumbar region shows similar sheet like of calcification in the dorso lumbar region just beneath the subcutaneous plane.
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MR scan of the cervical region reveals multiple hypointensities in both T1 and T2 weighted sequences in both para spinal muscles suggestive of calcification. Subtle T2 hyperintense signals are seen in the paraspinal muscles (edema) suggesting myositis.
Based on the symptomatology and imaging findings, diagnosis of Fibrodysplasia ossificans progressiva was made.
Myositis ossificans progressiva (also known as fibrodysplasia ossificans progressiva) is a severe, rare condition of ectopic ossification with primary involvement of the skeletal muscles, associated with characteristic skeletal abnormalities.
Genetics: It has autosomal dominant inheritance with complete penetrance but variable expressivity, and most cases result from a sporadic mutation. Genes for bone morphogenetic proteins, in particular BMP4, are thought to be plausible candidate genes. Mutations in the ACVR1 gene cause fibrodysplasia ossificans progressive.
The ACVR1 gene provides instructions for producing a member of a protein family called bone morphogenetic protein (BMP) type I receptors. The ACVR1 protein is found in many tissues of the body including skeletal muscle and cartilage. It helps to control the growth and development of the bones and muscles, including the gradual replacement of cartilage by bone (ossification) that occurs in normal skeletal maturation from birth to young adulthood.
Researchers believe that a mutation in the ACVR1 gene may change the shape of the receptor under certain conditions and disrupt mechanisms that control the receptor's activity. As a result, the receptor may be constantly turned on (constitutive activation). Constitutive activation of the receptor causes overgrowth of bone and cartilage and fusion of joints, resulting in the signs and symptoms of fibrodysplasia ossificans progressiva.
Clinical Course: Ectopic ossification usually starts in early childhood. Radiological evidence of ossification is not usually present until 4–6 weeks after the appearance of a lump. Sites of ossification include the neck, spine and shoulder girdle. Trauma precipitates new lesions. The ESR may be elevated during an acute episode. Radiological abnormalities of the toes and thumbs are common (Hallux valgus as in our case).
Imaging Studies :
Histopathology : Histologically, early lesions resemble granulation tissue, occasionally with cellular inflammatory infiltrate. Spicules of bone appear in the centre of the fibroblastic nodules. Bone and cartilage formation is seen in mature specimens. The bone formed initially is of the woven type; this is later remodelled to mature lamellar bone.
Management : There is little convincing evidence that any form of treatment alters the progress of the disease in myositis ossificans progressiva. Treatments that have been used include a diet reduced in vitamin D and calcium, the avoidance of sunshine, and treatment with corticosteroids. Other treatment strategies include beryllium, vitamins B and E and penicillamine. Drugs that block calcification have also been used, including EDTA (disodium ethylene diamine tetraacetic acid), isotretinoin and etidronate , without proven benefit.