Review Article
The Stone Man: Myositis Ossificans Progressiva, About a Case
Hind Boukhalit1,2*, Amal Lahfidi1,2 and Nazik Allali1,2
1Department of Radiology, Children’s hospital, Morocco
2Faculty of Medicine and Pharmacy, Mohammed V University, Morocco
Submitted: 10 May 2019; Accepted: 15 June 2019; Published: 18 June 2019
Cite this article: Boukhalit H, Lahfidi A, Allali N (2019) The Stone Man: Myositis
Ossificans Progressiva, About a Case. JSM Radiol Radiat Ther 5: 4.
Progressive ossificans myositis (MOP), also known as
progressive ossificans fibrodysplasia (FOP) or Munchmeyer’s
disease or stone man’s disease, is a rare genetic disorder
with autosomal dominant inheritance characterized by a
congenital malformation of the big toes and progressive
postnatal development of heterotypic ossifications of tendons,
ligaments, fasciae, connective tissues and skeletal muscles.
Initially described by Patin in 1648, then by Munchmeyer in
1869. Beginning generally before the age of 10, this heterotypic
ossification evolves by pushing along a cranio-caudal and dorsoventral
path leading to a disabling joint stiffness. Patients see
themselves trapped in a “second skeleton” [1].
ACVR1 (active in receptor type 1A) is the gene responsible
for FOP, identified in 2006 by KAPLAN and SHORE. It is located
on the long arm of chromosome 2 and it encodes the receptor
for BMP (Protein Bone Morphogenetic) protein that induces
the formation of bone and cartilage. ACVR1 is common to any
individual but the disease only occurs if one of the two copies of
this gene contains an abnormality [2].
We report a case of MOP observed in 10-year-old boys
to show the epidemiological, etiopathogenic, diagnostic and
therapeutic aspects.
Unjeune garçon de 10 ans sans antécédents familiaux
particuliers, présentant depuis l’age de 4 ansdes tuméfactions
douloureuses para vertébralesnégligées, évoluant vers
l’installation d’une cyphose dorsale, l’ankylose des deux membres
supérieurs et uneimpotence fonctionnelle invalidanteàl’examen
clinique.
le scanner thoraco-abdominopelvienmettait en évidencedes
ossifications extra-squelettiquesde la musculature para
vertébrale depuis l’occiput jusqu’au coccyx, ces ossifications
présentant des ramifications bilatérales et asymétriquespassant
par les régions sous scapulaires, fusionnant avec les extrémités
supérieures des humérus, arrivant à la paroi thoracique
antérieure, réalisant l’aspect de l’homme en pierre,le diagnostic
de myosite ossifiante progressive a été retenu eta été confirmé
par l’étude génétique.
10-year-old boy with no consanguineous parents and none
of the family members problem, presenting since the age of 4
neglected paravertebral painful swelling, moving towards the
installation of a dorsal kyphosis, the ankylosis of both upper
limbs and disabling functional impotence, Laboratory blood tests
for calcium, phosphorus, alkaline phosphatase, urea, creatinine
and parathyroid hormone found normal values.
The thoraco-abdomino-pelvic CT scan was performed
without IV contrast (Figure 1) and showed extra skeletal
ossifications in the paravertebral musculature from the occiput to
the coccyx, these ossifications having bilateral and asymmetrical
ramifications through the sub-scapular regions, merging with the
upper extremities of the humerus, arriving at the anterior chest
wall, realizing the appearance of the stone man, the diagnosis of
progressive myositis ossificans was retained and was confirmed
by the genetic test (Figure 2).
-
Figure 2: Thoracic CT scan with reconstruction: significant extra
skeletal and skeletal ossification engaining the posterior face of the
trunk, merging with the upper ends of the humerus, associated with
other parasternal and paravertebral cortical ossifications bilaterally
and a dorsal kyphosis. View Figure
MOP extremely rare genetic condition, affects on average 1
person in 2 million. Described for the first time in 1648 by PATIN
[3]. This condition is mainly described in young children and affects both sexes equally: 41% of MOP is screened before the
age of 2 years, 80% before 10 years and 95% before 15 years [4].
Our case is in harmony with the literature, the first symptoms
having appeared at the age of 4 years. Ethnicity, race, gender, or
geography do not appear to be predisposing factors, however
a genetic factor is likely with the occurrence of a spontaneous
mutation of the ACVR1 gene on chromosome 4 of autosomal
dominant inheritance. Encoding a BMP4 protein receptor involved
in the growth and modeling of bone [5]. The symptomatology of
the MOP associates a fever with the appearance of inflammatory
swellings affecting the connective tissues and the muscles. These
will ossify and gradually spread to all areas of the body. This
process initially affects the neck and paravertebral muscles with
extension in a proximo-distal and cranio-caudal pattern [6]. The
attacks will then touch the shoulders and then the lumbar spine
and hips. Later distal joints can be reached by the 3rd decade of
life. However according to Munchmeyer, muscles that do not fit
on the skeleton by their two ends are spared. This explains the
respect of the ocular muscles, the diaphragm, the tongue, the
pharynx, the larynx and the smooth muscles (Figure 3) [6].
-
Figure 3: Thoracic CT scan with the axial and sagittal planes: show extra-skeletal ossifications of the para-vertebral musculature, with bilateral
and asymmetrical ramifications through the sub-scapular regions, merging with the upper ends of the humerus, reaching the anterior chest wall. View Figure
Our case is similar to the target muscle and lesion progression
literature and tends to confirm Munchmeyer’s hypothesis. On the
other hand, 70-100% of the cases show mainly bone defects in
the thumbs and the big toes [6]. They are clinically translated
into a micro typing and a bilateral Hallux valgus. Other more
rare and varied malformations are described such as vertebral,
epiphyseal, rotulian, calcaneous spines, the femoral cervix, the
fifth fingers or thickening of the inner cortical of the tibia. Does
not exist in our case. Patients with atypical forms of FOP have
been described, either the classic signs of FOP are present, with
one or more atypical signs (for example: inters current aplastic
anemia, craniopharyngioma, infantile glaucoma or stunting), either one or both cardinal signs of FOP show major variations
for example, large normal toes or severe reduction of fingers
(FOP variants). Due to ankylosis of the costo-vertebral joints and
vertebral deformation, patients end up developing restrictive
respiratory insufficiency with atelectasia. Pneumonia and right
heart failure can be fatal. Biological examinations are part of the
diagnostic elements of the MOP but they have little therapeutic
interest, evolution and prognosis [7]. The minimum number of
biological examinations to be requested is related to the bone
metabolism including the phosphocalcic balance and the level of
PAL and that relating to the inflammatory process including the
VS and the blood count [7].
Conventional radiology is the key to diagnosis by showing
evocative images such as ectopic cortical calcification of affected
and advanced muscles, bone bridges between different parts of
the skeleton with a true ectopic skeleton. It also shows typical
congenital bone malformations. Other imaging means are not
necessary for diagnosis, especially at an advanced stage. The
scanner makes it possible to better analyze the ossifications as
well as their extent thanks to the multi planarian reconstructions
as observed in our patient.MRI and scintigraphy may show
lesions that are not yet ossified [8]. The diagnosis of FOP is radioclinical
and does not require a biopsy that may be the starting
point for ectopic ossification and may be misleading because of
the heterogeneous nature of the lesions [8].
Several differential diagnoses can be mentioned especially
at the beginning of the disease and when the toes and fingers
are not examined. Ossifying metastases, ossified hematomas, calcifying tendinopathies, exotic diseases, circumscribed
ossifying posttraumatic myositis that is usually limited to a
single location, delimited, and painful, that occurs as a result of
trauma. Soft tissue sarcomas may be discussed on biopsy results
of early lesions [9,10]. Hereditary osteodystrophy of ALBRIGHT
is characterized by ossification in muscle and connective tissue,
but is more marked in subcutaneous fat and associated with
pseudohypoparathyroidism [11]. Ankylosing spondylitis may be
referred to ankylosis of the spine and sacroiliac joints [12]. The
natural history of this condition is characterized by inflammatory
outbreaks of 2 to 3 weeks, interspersed by periods of latency
more or less long. The development may be enamelled by the
occurrence of several thromboembolic, neurological, skin,
infectious or respiratory complications. Its prognosis depends
mainly on the occurrence of respiratory failure at a late stage.
To date, no treatment has proven effective. However, several
therapeutic means are proposed in the management of MOPs [3].
Mild physiotherapy is proposed for analgesic purposes during
surges. Drug treatment includes corticosteroids, mastocyte
inhibitors, cyclooxygenase 2 inhibitors, non-steroidal antiinflammatory
drugs, amino biphosphonates, BMP antagonists,
anti-angiogenic agents or retinoids with still random and
unsatisfactory results. Their use must be weighed against the
potential severity of their side effects. There is little room for
surgery, especially since anesthesia in these patients is difficult
because of spinal rigidity and mandibular fixation [13,14].
Surgical removal of these ossifications to mobilize the joints
is a new trauma that promotes the development of additional
heterotopic ossifications. The sole purpose of the surgery is to
correct the vicious attitudes to give stiffness in a most favorable
position possible. In front of the limits of medical and surgical
treatments, prevention becomes very important. Several
measures can limit the evolution of the disease: prevention
of trauma, mandibular blockage, rehabilitation medicine and
physiotherapy with respiratory physiotherapy [15].
An extremely rare condition, MOP should be reported in any child with an unexplained inflammatory mass, associated with
heterotopic ossification of the soft parts and congenital bone
abnormalities. His diagnosis is radio-clinical. The development is
marked by the appearance of particularly disabling joint stiffness.
It can also involve the vital prognosis of general complications.
No effective preventive or curative treatment is available to date.
Nevertheless, several molecules are currently being tested.