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 Table of Contents  
Year : 2021  |  Volume : 16  |  Issue : 3  |  Page : 359-360

Fibrodysplasia ossificans progressiva: “A skeleton within a skeleton”

Department of Clinical Immunology and Rheumatology, King George's Medical University, Lucknow, Uttar Pradesh, India

Date of Submission22-Jan-2021
Date of Acceptance22-Jan-2021
Date of Web Publication21-Sep-2021

Correspondence Address:
Dr. Anupam Wakhlu
Department of Clinical Immunology and Rheumatology, King George's Medical University, Lucknow - 226 003, Uttar Pradesh
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/injr.injr_19_21

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Keywords: FOP, Heterotopic ossification, hallux valgus

How to cite this article:
Hazarika K, Ekbote DG, Sahoo RR, Krishnan A, Wakhlu A. Fibrodysplasia ossificans progressiva: “A skeleton within a skeleton”. Indian J Rheumatol 2021;16:359-60

How to cite this URL:
Hazarika K, Ekbote DG, Sahoo RR, Krishnan A, Wakhlu A. Fibrodysplasia ossificans progressiva: “A skeleton within a skeleton”. Indian J Rheumatol [serial online] 2021 [cited 2021 Nov 27];16:359-60. Available from:

A 20-year-old young male presented with gradually progressive restriction of mouth opening for the past 1 year, with severe restriction in the past 3 months. He had a severely deformed back since childhood. A small nodule was noticed by his mother over his back during routine massage from the age of 2 months, which became stony hard over the coming months. At around 2 years of age, he had a trivial fall on the back, following which the neck-and-back muscles gradually started to harden with pain, and by the age of 10 years, his back had become severely deformed. He received numerous therapies to no avail. Examination revealed severe restriction of mouth opening (4 mm only). The neck-and-back muscles were bony hard in segments, leading to severe kyphoscoliosis and pelvic tilt. The patient had bilateral congenital hallux valgus deformity with characteristic shortening of the great toe. Roentgenograms of cervical, thoracolumbar spine, pelvis, and chest revealed heterotopic ossification of various muscles. Computerized tomography (CT) of the skull showed ossification of the pterygoid muscle, contributing to the restriction in mouth opening. A diagnosis of fibrodysplasia ossificans progressiva (FOP) was made in view of classical clinical features, bilateral hallux valgus with short great toes, and heterotopic ossification of muscles and ligaments [Figure 1]a, [Figure 1]b, [Figure 1]c, [Figure 1]d,[Figure 1]e, [Figure 1]f, [Figure 1]g. A whole body CT scan with three- dimensional reconstruction showed heterotopic ossification along the spine, chest wall and left lower limb as well, forming “a skeleton within a skeleton” [Figure 2]a, [Figure 2]b. The patient was the only affected child, with two normal siblings, born to normal parents in a non-consanguineous marriage, suggesting a sporadic occurrence. FOP is a rare genetic disease, characterized by heterotopic ossification of soft tissues spontaneously or on minimal trauma. Most cases are known to occur sporadically without definite predilection to gender, race, or geographic distribution. Autosomal dominant germline transmission is known to occur in a few cases. The estimated prevalence is around 1 in 2 million.[1] Diagnosis is mainly clinical which can be bolstered by genetic studies to detect mutations or deletions in the ACVR1/ALK2 gene.[2] Except for the management of flares with high-dose corticosteroids, no other therapy has been found to be useful. Biopsies, surgeries, and intramuscular injections are better avoided.[3]
Figure 1: Clinical and imaging characteristics of fibrodysplasia ossificans progressiva (FOP). (a) Deformed spine with ossification of neck and paravertebral muscles. (b) Bilateral hallux valgus deformity with shortening of great toes. (c) Severely restricted mouth opening. (d) X-ray cervical spine lateral view revealed vertebral fusion with prevertebral soft-tissue calcification (left arrow) and ossification of trapezius muscle (right arrow). (e) X-ray lumbosacral spine lateral view showing ossification of paravertebral muscles and ligaments with severe deformity (arrows). (f) X-ray chest posteroanterior view showing ossification of intercostal muscles (arrow) and scattered calcification in the chest wall. (g) Computerized tomography image of skull and jaw showing ossification of the pterygoid muscles (arrow).

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Figure 2: Whole body computerised tomography( CT) with three-dimensional (3D)reconstruction (a) antero-posterior view and (b) postero-anterior view showing heterotopic ossification of muscles (arrows)

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Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given his consent for his images and other clinical information to be reported in the journal. The patient understands that name and initials will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed.

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Conflicts of interest

There are no conflicts of interest.

  References Top

Pignolo RJ, Shore EM, Kaplan FS. Fibrodysplasia ossificans progressive: Clinical and genetic aspects. Orphanet J Rare Dis 2011;6:80.  Back to cited text no. 1
Kaplan FS, Xu M, Seemann P, Connor JM, Glaser DL, Carroll L, et al. Classic and atypical fibrodysplasia ossificans progressiva (FOP) phenotypes are caused by mutations in the bone morphogenetic protein (BMP) type 1 receptor ACVR1. Hum Mutat 2009;30:379-90.  Back to cited text no. 2
The International Clinical Council on FOP (ICC) and Consultants. The Medical Management of Fibrodysplasia Ossificans Progressive: Current Treatment Consideration. March 2019. Available from: [Last accessed on 2021 Jan 15].  Back to cited text no. 3


  [Figure 1], [Figure 2]


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