Nigerian Journal of Paediatrics

12Hereditary multiple exostoses in a 15 year old boy A case report and review of literature

Niger J Paediatr 2016; 43 (4): 295 – 298

CASE REPORT

Eke GK

Hereditary multiple exostoses in a

Omunakwe HE

Echem RC

15-year-old boy: A case report

and review of literature

DOI:http://dx.doi.org/10.4314/njp.v43i4.12

Accepted: 6th September 2016

Abstract : Background: Heredi-

These swellings were non-tender,

tary Multiple Exostoses (HME) is

not attached to the overlying skin

Eke GK (

)

a rare bone disease, usually asso-

and immobile, had no differential

Department of Paediatrics,

ciated with deformity and pres-

warmth and appeared to be con-

Omunakwe HE

sure symptoms. It is an autosomal

tinuous with the underlying bony

Department of Haematology

dominant disorder characterized

structures. A striking feature was

by the development of benign

exostoses that extended from the

Echem RC

tumours growing outward from

lumbar spine towards the left scap-

Department of Orthopaedics,

the metaphyses of long bones and

ula. He also had brachymetatarsia

University of Port Harcourt Teaching

can lead to considerable psycho-

of the first ray of both feet. Skele-

Hospital, Port Harcourt, Rivers State,

social problems. This paper aims

tal survey confirmed the diagnosis.

Nigeria.

at reporting a case of HME with

Conclusion: Though rare, HME do

Email: kergracia@yahoo.com

some peculiar features.

occur in our environment. The

Methods: A case report of a 15-

treatment is individualized, with

year-old Nigerian male with He-

small asymptomatic or minimally

reditary Multiple Exostoses is

symptomatic lesions followed up

presented to highlight the clinical,

and only supportive care provided.

radiological features and manage-

Larger symptomatic lesions may

ment challenges of the condition.

cause major physical handicap and

Results: The patient presented

may be resected.

with multiple hard, bony and

ridge-like growth along the spine,

Key words : Hereditary, Multiple,

scapula and para-vertebral region

Exostoses, Deformity

which gradually increased in size.

Introduction

It manifests more in early childhood to puberty and

40% of the affected children manifest before the age of

Osteochondroma, the most common bone tumour seen

10 years. Lesions have been infrequently reported to

in children, is a developmental lesion rather than a true

spontaneously regress during the course of childhood

and puberty.

3,10

neoplasm and constitutes 20% – 50% of all benign bone

tumours. It is a cartilage-capped exostosis found pri-

The commonest complications of this condition are de-

marily at the juxta-epiphyseal region of the most rapidly

formity, pressure symptoms and malignant degenera-

growing ends of long bones.

Hereditary Multiple

tion.

1,3,4,5

Diagnosis is based on clinical examination and

Exostosis (HME), also known as diaphyseal aclasia and

radiographic evaluation, while treatment of osteochon-

multiple osteochondromatosis, is characterized by the

droma is individualized, depending on the presentation.

In Nigeria, cases of HME have also been reported,

11,12

development of multiple osteochondromas (exostoses)

and is frequently associated with characteristic progres-

affecting the lower and upper limbs while the index pa-

sive skeletal deformities.

3-6

The disorder shows an auto-

tient had in addition massive exostoses which extended

somal dominant inheritance pattern with approximately

from the lumbar spine towards the left scapula. This was

two-thirds of affected individuals having a positive fam-

not a common feature in cases reported in the literature.

ily history. The earliest known description of an af-

The aim of this paper is to report a case of hereditary

flicted family was reported by Boyer in 1814.

3,7

multiple exostoses with some peculiar features.

The true prevalence of HME is not known since many

patients with asymptomatic lesions are never diag-

Case report

nosed. However, its estimated prevalence is 1:50,000 to

1:100,000 in Western populations and may be as high as

K.V, a 15-year old Nigerian male was referred from a

1:1,000 in the Chamorros, the indigenous people of

public secondary level health care facility and presented

Guam and the Mariana Islands.

1,8

Although previously

to the Children Out-patient Clinic of the University of

thought to have a male predominance, HME now ap-

Port Harcourt Teaching Hospital (UPTH) in Rivers

pears to affect both sexes similarly.

3,9

State, Nigeria because of a 3-year history of multiple

296

swellings on the back.

These developed over his lower back along the midline

and over the lateral and upper aspects of his back as

multiple swellings which gradually increased in size and

eventually coalesced in certain areas, causing a deforma-

tion of his back with difficulty in bending his trunk and

inability to freely turn his head to both sides. He had

mild pain when lying on his back. There was no preced-

ing history of trauma and no other constitutional symp-

toms.

He had herbal concoctions with scarifications before

Fig 1a: Photograph of the

Fig 1b: Photograph of a closer

presenting at the referral health facility for worsening of

patient’s back

view of the legs and feet

limitation of movements of the neck and trunk.

He was said to have developed similar swellings at 10

months of age over his trunk, no x-ray was done for con-

firmation,which lasted about 6 months and regressed

spontaneously. However they re-occurred 3 years prior

to presentation, when patient was 12 years old.

An average grade 7 student (JSS1), he had not attended

school for the last 1 year because of worsening limita-

tion of his movements. He is the last of 8 children, 5

alive, in a monogamous family setting. His mother was

a farmer with no formal education, while his father died

of a chronic illness 7 years prior to child's presentation.

There was no history of similar illness in the family and

they reside in an oil producing area of the Niger Delta

Fig 1c: Photograph of the patient Fig 2: X-ray of thoraco-

region with petroleum exploratory activities and recur-

lumbar spine from the front

rent oil spillages in the community as well as past his-

tory of communal clashes with use of explosives and

other local war artillery. Their source of drinking water

is well water which is not boiled.

Physical examination revealed a withdrawn adolescent,

in no obvious respiratory or painful distress. There was

asymmetry of the pectoral girdle, marked left-sided sco-

liosis, neck stiffness with limited rotational movement

of the head. Masses along the spine, scapula and para-

vertebral regions were multiple, hard, bony, rounded and

ridge-like, some measuring up to 6x8cm, non-tender, not

attached to the overlying skin and immobile, with no

Fig 3: Chest X-ray showing

Fig 4: X-ray of both legs

differential warmth, appearing to be continuous with the

exostoses from rib cage

showing exostoses at the

underlying bony structures (Fig1). There were also knob

proximal tibia

-like hard bony swellings over the lateral aspect of the

upper one-third of the left leg with a similar protrusion

over the right lateral maleoli. He had brachymetatarsia

of the first ray of both feet (Fig1). There was no neuro-

Discussion

logical deficit. His height was 156cm. Skeletal survey

(Fig.2,3 and 4) confirmed the diagnosis of HME.

Hereditary Multiple Exostoses (HME) is a genetically

He was admitted for investigations and co-managed

heterogeneous disorder and has been associated with

with the orthopedic surgeons, physiotherapist and social

mutations in at least three different genes, termed EXT

workers. Counselling was offered, excision of some of

genes. At least two of these genes are thought to func-

tion as tumour suppressor genes.

3,4,6

the exostoses especially those on the back was advised

These mutations

as well as genetic studies.However, he signed against

may disrupt normal cartilage growth, resulting in the

formation of an osteochondroma. The three described

medical advice, stating financial constraints as main

reason, and had since been lost to follow up.

EXT loci have been recently mapped: EXT1 on chromo-

some 8q23-q24, EXT2 on 11p11-p12, and EXT3 on

chromosome 19p. According to linkage analysis, the

EXT1 and EXT2 loci appear to be altered in the major-

ity of families while, EXT3, which has not been fully

isolated and characterized, is probably less frequently

affected.

3,4,6

Epidemiologic analysis of linkage and mu-

297

tation data indicate that mutations of EXT1 and EXT2

the late presentation. Osteochondromas that extend ante-

are likely to be responsible respectively for one half and

riorly from the vertebral body may produce symptoms

one third of MHE cases. Genetic studies were however

of dysphagia, hoarseness, and vascular compromise.

not conducted for the index patient.

Affected individuals may also show disturbance of

growth with short stature, wrist and ankle deformity and

Hereditary Multiple Exostoses is characterized by for-

mental handicap as had been reported by other workers

9,17

mation of ectopic, cartilage-capped, growth plate-like

but these features are variable and were not seen in

exostoses next to growing long bones and other skeletal

the index case.

elements. The exostoses usually originate proximal to

an active growth plate, may occur at or after birth and

The index patient had a history of similar swellings

throughout puberty, and may continue to grow slowly

around the trunk at the age of 10 months, which re-

3,9,13

during adulthood.

They form predominantly on the

gressed spontaneously after about 6 months. Earliest

physes of long bones, pelvis, ribs, scapula, and vertebrae

lesions may even be present at birth as had been re-

ported by Solomon. On the other hand, though uncom-

and begin to appear as early as 2 years of age.

9,11,14

Most

patients are diagnosed by age 5 years, and virtually all

mon phenomena, the pattern of spontaneous resolution,

are diagnosed by age 12 years. In families with the ge-

or appearance of new lesions years after excision of pri-

netic predisposition, members who do not demonstrate

mary osteochondromas have been previously docu-

mented, but the literature is limited.

10,18

lesions by age 12 years will not manifest the disease.

Brachymetatarsia

After adolescence and skeletal maturity, osteochondro-

of the first ray of both feet were present in the index

mas usually exhibit no further growth.

patient. The feet can be involved in HME as had been

reported by other workers.

8,9

There is scarcity of reported cases of MHE in Nigeria.

This may be because of under-reporting rather than non

Complications commonly associated with these exo-

occurrence seeing that two reports of this rare autosomal

phytic masses include cosmetic and osseous deformity,

dominant disorder were found. Yinusa et al reported 2

pressure symptoms, fracture, vascular compromise, neu-

cases, a 13-year-old girl and a 9-year-old boy, who pre-

rologic sequelae, overlying bursa formation, and malig-

sented at an orthopaedic hospital within a six months

nant transformation. Of these, outstanding complications

period, whilst Adelowo and Adebayo reported the dis-

in the index patient were cosmetic deformity, restricted

ease in two siblings, both of whom are children of an

joint movements affecting the vertebral joints, the upper

achondroplastic father.

and lower limbs and pain. This is of great concern as the

patient was already out of school because of these com-

Whereas all cases reported in Nigeria presented with

plications, possibly facing physical, psychological and

clinical and radiological features of HME affecting the

social distress which have a negative impact on his qual-

lower and upper limbs, the index case had in addition

ity of life.

massive exostoses on the spine, scapulae and ribs (Fig.1,

Fig 2, Fig 3 and Fig 4). One of the peculiar features with

Malignant transformation has been reported, with docu-

this patient was the exostoses which extended from the

mented risk of 1-6% in patients with HME in adulthood,

lumbar spine towards the left scapula, an unusual feature

with chondrosarcoma developing more frequently than

osteosarcoma.

1,3-5,8,9,17,19

in cases reported in the literature. We wonder if there

Higher estimates of 10-25%

could be any factors responsible for the elongation. This

have been cited but they have been a function of bias

is a subject that will require further research.

and incomplete detection of affected individuals who did

not have a sarcoma but were members of a family that

had exostoses.

8,9

Central exostoses involving the skull base, spine, or rib

Lesions that grow or cause pain after

heads are seen in 1% – 9% of patients with HME, and

skeletal maturity should be suspected of malignant

may cause cranial nerve deficits, radiculopathy, spinal

transformation which is distinctly unusual before the age

stenosis, cauda equina syndrome, myelomalacia and

of 20. The index patient should therefore be kept under

spinal cord compression.

1,15,16

Interestingly, in patients

regular review both clinically and radiologically to

with HME, spinal lesions are usually solitary. The cervi-

evaluate progression of deformities and development of

cal spine is most frequently affected (50% of lesions),

complications.

followed by the thoracic and the lumbar spine. Lesions

The diagnosis depends largely upon X-rays while the

that protrude dorsally from the posterior vertebral ele-

radiographic appearance of a lesion composed of bone

ments (lamina or spinous process) are typically large

demonstrating cortical and medullary continuity with the

underlying parent bone is often pathognomonic. Le-

and manifest at an earlier age with cosmetic deformity

and palpable mass but lack neurologic symptoms. In

sions that involve complex areas of anatomy (spine or

contradistinction, osteochondromas that extend into the

pelvis) are frequently better assessed with CT or MR

spinal canal are often small but are associated with neu-

imaging to detect the characteristic marrow and cortical

continuity.

16,20

rologic symptoms. It is therefore not surprising that

Bone scintigraphy has been demonstrated

despite the considerable size of the spinal lesions caus-

to be useful in the periodic surveillance of adult patients

with HME.

ing limitation of range of flexion and extension of the

A biopsy should be done in doubtful cases

and to help assessing malignant degeneration.

trunk and significant deformity, the index patient had no

neurological deficit. The fact that the deformity was on

Differential diagnosis include Dysplasia Epiphysealis

the back, usually covered with cloths, could account for

Hemimelica (DEH) or Trevor's disease, which is

298

transmitting the disorder to his offspring.

4,7,22

described as a type of over growth at one or more

epiphyses, and metachondromatosis, a rare disorder that

exhibit symptoms of both multiple osteochondromas and

enchondromas in children and is also inherited in auto-

somal dominant mode.

Conclusion

Treatment of HME is individualized and much more

problematic and complex than that of patients with soli-

Though rare, HME do occur in our environment. The

tary osteochondromas. Small asymptomatic or mini-

treatment is individualized, with small asymptomatic or

mally symptomatic lesions are followed up and only

minimally symptomatic lesions followed up and only

supportive care provided while larger symptomatic le-

supportive care provided. Larger symptomatic lesions

sions may be resected. Thus, depending on the deform-

may cause major physical handicap and may be

ity, the surgical intervention may involve corrective os-

resected.

teotomy, epiphysiodesis, excision or limb lengthening.

Introduction of palliative care and health insurance cov-

Surgical treatment is often directed at correcting the

erage for rare disorders of childhood are recommended

associated deformities rather than restricted to the

to improve outcome.

exostoses alone. The surgeries may be multiple thus, the

psychological effect on the patient should be considered.

Conflict of interest: None

Genetic counselling is an important aspect of the man-

Funding: None

agement of HME as each individual is at 50% risk of

References

1. Murphey MD, Choi JJ, Krans-

10. Stitzman-Wengrowicz M, Pre-

17. Welsh GA, MacLeod I.

dorf MJ, Flemming DJ,

tell-Mazzini J, Dormans J,

Diaphyseal aclasis affecting

Gannon FH. Imaging of osteo-

Davidson R. Regression of a

the temporomandibular joint.

chondroma: variants and com-

sessile osteochondroma: A case

Dento maxilla fac Radiol

plications with radiologic-

study and review of the litera-

1999; 28: 320- 323.

pathologic correlation. Radio-

ture. University Pennsylvania

18. Morton KS. On the question

graphics 2000; 20 : 1407-1434 .

Orthopedic J 2011; 21: 73-76

of recurrence of osteochon-

2. Peterson HA. Multiple heredi-

11. Yinusa W, Owoola AM, Esin

droma. J Bone Joint Surg

tary osteochondromata. Clin

IA. Hereditary multiple exosto-

1964; 46: 723-725.

Orthop Relat Res 1989; (239):

sis: case report. Niger J Clin-

19. Human L. Diaphyseal aclasis:

222 – 30.

Pract 2010; 13: 218-222.

Review of literature and report

3. Stieber JR, Pierz KA, Dormans

12. Adelowo O, Adebayo S. He-

of an unusual case. S Afr Med

JP. Hereditary multiple exosto-

reditary multiple exostoses in

J 1965; 39: 27-29.

ses: a current understanding of

two Nigeria siblings. BMJ

20. Vanhoenacker FM, Van Hul

clinical and genetic advances.

Case Rep 2009;

W, Wuyts W, Willems PJ, De

University Pennsylvania Or-

2009.pii:bcr09.2008.0901 .

Schepper AM. Hereditary

thopaedic J 2001; 14: 39 – 48.

13. Zak BM, Schuksz M, Koyama

multiple exostoses : from ge-

4. Bovee JV. Multiple osteochon-

E, Mundy C, Wells DE, Yama-

netics to clinical syndrome

dromas. Orphanet J Rare Dis

guchi Y. et al . Compound het-

and complications. Eur J Ra-

2008; 3 :3.

erozygous loss of EXT1 and

diol 2001; 40: 208-217.

5. Richardson RR. Variants of

EXT2 is sufficient for forma-

21. Epstein DA, Levin EJ. Bone

exostosis of the bone in chil-

tion of multiple exostoses in

scintigraphy in hereditary

dren. Semin Roentgenol 2005;

mouse ribs and long bones.

multiple exostoses. AJR Am J

40:380-390.

Bone 2011: 48; 979-987.

Roentgenol 1978; 130: 331-

6. Pannier S, Legeai-Mallet L.

14. Roehl HH, Pacifici M. Shop

333.

Hereditary multiple exostoses

talks: Sugars, bones, and a dis-

22. Crandall BF, Field LL,

and enchondromatosis. Best

ease called multiple hereditary

Sparkes RS, Spence MA. He-

Pract Res Clin Rheumatol

exostoses. Dev Dyn 2010; 239:

reditary multiple exostoses.

2008; 22: 45-54.

1901-1904.

Report of a family. Clin Or-

7. Hennekam RC. Hereditary

15. Labram E, Mohan J. Diaphy-

thop Relat Res 1984; (190):

multiple exostoses. J Med

seal aclasis with spinal cord

217-219.

Genet 1991; 28: 262-266.

compression. Report of two

8. Schmale GA, Conrad EU 3 ,

cases and review of the litera-

Raskind WH. The natural his-

ture. J Neurosurg 1996; 84:

tory of hereditary multiple

518-521.

exostoses. J Bone Joint Surg

16. Bess RS, Robbin MR, Bohlman

Am 1994; 76: 986-992.

HH. Spinal exostoses: analysis

Solomon L. Hereditary multi-

of twelve cases and review of

ple exostosis. J Bone Joint

the literature. Spine 1976 2005;

Surg Br 1963; 45:292-304 .

30: 774-780.