Thoracic and lumbar spines are the most affected parts of the
vertebral column [3].It usually starts in the posterior part of the vertebral
body, and with its expansile nature, it can extend anteriorly causing
destruction of the body and spinal cord compression with neurological symptoms[3,5],so
it is a benign locally aggressive bone tumor. Aneurysmal Bone Cyst (ABC) can be
of two types; primary (de novo) ABCs, which represents about 70 % of all ABCs,
and secondary ABCs with multiple hemorrhages, which develop most of the times
due to cystic degeneration in a background of giant cell tumor, osteoblastoma,
chondroblastoma, or fibrous dysplasia of bone [3,7].
Treatment options:
Treatment options of the spinal ABCs are still controversial
ranging between surgical and non-surgical options being available according to
the case [3,5].Non-surgical options include selective arterial embolization of
the feeding vessels, intralesional calcitonin or steroid injection.Radiotherapy is another option for those unresectable huge
ABCs, or post incomplete surgical excision of the cyst as an adjuvant therapy,
with the increased risk of radiotherapy associated osteonecrosis and myelopathy
[3].For the surgical options in treating ABCs, the best to do is
a wide local resection to prevent, or to intra lesional curettage with bone
grafting. If the cyst is too big, you can augment the body with Polymethyl
Methacrylate (PMMA) bone cement to enhance stability. In most cases of surgical
resection, instrumentation of the spine is mandatory for early rehabilitation
Case
Description
A 12 years old female
patient with no previous significant medical or surgical history, was referred
to our hospital 20 days post admission to a public local hospital with a
history of progressive lower limbs weakness and parasthesia associated with progressive
urine and stool incontinence, in the form of inability to void urine
voluntarily, and abdominal pain associated with constipation. She had already
presented on referral with Foley’s catheter in situ from the referring hospital.
Taking history from the patient revealed that her symptoms were associated with
mid back pain; there was no history of trauma or past history of back surgery,
and no family history of neuromuscular disorders.
Upon examination of the patient, she was in pain, depressed
and a little bit pale. Her systemic examination was within normal limits, with
no abnormal findings apart from mildly distended abdomen with mild generalized tenderness
due to constipation and gaseous bowel, and bladder was not palpable because of
Foleys catheter. Conducting rectal exam for our patient showed increased tone
of anal sphincter with loss of voluntary anal contraction. There were no
palpable back masses or obvious deformities.Examination of the lower limbs showed symmetrical bilateral
hypertonia with difficult passive range of motion bilaterally in both ankles
and knees. Muscle power was absent in both lower limbs except for toes
flickering in left side. Touch and pin prick sensation was diminished up to a
groin level. Knee and ankle reflexes were exaggerated and brisk bilaterally.
Examination of both upper limbs was within normal with no abnormal findings.Laboratory investigation for our patient showed normal
Erythrocyte Sedimentation Rate (ESR) and Normal C-Reactive Protein (CRP),
normal kidney and liver function tests, and normal hemoglobin level and normal
white blood cells count.Collecting previous data together indicated that the patient
had a central cord problem, so next step was to do imaging studies for the patient.
Anterior-Posterior (AP) radiograph for the whole spine and the pelvis was not
informative because of gaseous abdomen , and lateral radiograph for the whole
spine could not be done because the patient could not stand.
Next, we did Computerized Tomography (CT) Scan for the
thoracolumbar spine of the patient that showed a destructive expansile bony
lesion with egg shell bony margins involving the posterior elements of the 10th
and 11th thoracic vertebrae, as well as the pedicles and extending
to the posterior two thirds on the left side of the 11th thoracic
vertebral body associated with soft tissue element (Figure 1), so
Magnetic Resonance Image (MRI) was done.
Magnetic Resonance Image (MRI) with contrast revealed an expansile
multicystic lesion involving the left side body, pedicle, lamina and spinous
process of the 11ththoracic vertebra (T11), and the lamina and
spinous process of the 10th thoracic vertebra (T10), containing
fluid-fluid levels and causing severe compression of the spinal cord pushing it
anteriorly and to the right side. The lesion showed minimal septal enhancement (Figure
2).and by combining the data from both the CT scan and the MRI and the
clinical data all together, the most likely differential diagnosis for the
Radiological findings for this patient was Aneurysmal bone Cyst .
Management
As the diagnosis of
ABC was radiologically confirmed, our patient was planned for catheterization
and selective embolization of the feeding vessels as a preparation for the
surgery to be done. Our interventional radiologist successfully embolized the
lesion following complete investigation
of the patient (Figure 3).
Surgery was planned for the patient within the next (48)
hours post embolization, especialy with the significant spinal cord compression
and lower limbs paralysis. Surgery was done within (48) hours with the plan of
doing long segment instrumentation, intra lesional curettage and bone grafting.
This was done by a posterior approach only. Muscles were dissected from the
tumor boundaries easily. Three levels above and three levels below the involved
vertebrae were instrumented. The posterior elements of the 10th and
11th vertebrae were dissected and excised en-block and the cord was
significantly decompressed. Aggressive curettage for the body of T11was done
and synthetic bone graft was done for the cavity (Figure 4). All tissues
removed were sent for histopathological examination No significant bleeding
occurred intraoperatively and no blood transfusion was required. The
histopathology report confirms the diagnosis of Aneurysmal Bone Cyst, Solid
variant with no evidence of malignancy (Figure 5).
Follow up
Patient showed
significant improvement within the first few days post-operatively. The lower
limbs tone decreased and was back to normal within 48 hours post-surgery, and she
gained sensation for touch and painful stimuli 4-5 days post-operatively, with
good muscle power allowing her to stand up with the help of the physiotherapist
, fourth day post-operatively. Foleys
catheter was removed on the seventh day post operatively and the patient was
able to control urination and defecation within two weeks post operatively. The
patient was walking independently with full power and full sensation of both
lower limbs, and well controlled urination, well controlled defecation, and
clean dry wound 20 days post admission (Figure 6).
Patient was on regular follow up at our clinic for the last 3
years; she showed no alarming signs or symptoms with no any clinical or
radiological evidence of recurrence.
Radiographs were done every six months and are within normal
limits. Computerized Tomography (CT) Scan and Magnetic Resonance Imaging (MRI) were
done at one year and two years follow up visits, which showed complete
consolidation of T11 vertebral body with no evidence of recurrence (Figure 7).
DISCUSSION
Aneurysmal Bone
Cyst (ABC) can cause significant morbidity if delayed in diagnosis or
inappropriately treated, even if it is a benign pathology.[3, 4, 6].The symptoms of ABC can be present few months prior to
diagnosis, and localized pain is the main presenting symptom in most of the
patients which typically increases with recumbency. Some patients may come with
palpable tender mass, other patients may manifest with functional deformity due to pain and
muscle spasm. 60-70 % of the patients can initially show up with neurological
symptoms [3],ranging from parasthesia due to root compression up to complete
paralysis due to acute spinal cord compression. Accidental finding in a
pathological fracture can be the initial presenting symptom.Aneurysmal Bone Cysts ABCs are generally thought to be the
result of a secondary vascular phenomenon that develop on a background of a
preexisting lesion like an unnoticed fracture or preexisting subperiosteal
hematoma, which presumably initiates a periosteal or intraosseous arteriovenous
malformation[8].Histopathologically, it is better described as an expansile
osteolytic lesion consisting of blood-filled spaces lined by endothelial tissue
and separated by connective tissue septae containing osteoid like tissue and
osteoclast –like giant cells [8].
Treatment options are wide and controversial, ranging from
radiological, medical, and surgical treatment option, depending on the site, size,
and accessibility to the lesion, as well as the facilities and experience of
the surgeon.
Some ABCs can be treated conservatively when the diagnosis is
confirmed to be Aneurysmal Bone Cyst, and it is not causing any signs and
symptoms and it is not increasing in size [8].When the ABC is causing signs and
symptoms and is not accessible by surgery and complete surgical resection was
not done, then radiotherapy or intralesional injections trials can be done
[3,5].Complete surgical excision or intralesional curettage and grafting
is still the best option for symptomatic young patients, with the best short
and long-term outcome and preventing recurrence.Preoperative selective arterial embolization for the cyst will
make surgery easier and decrease the rates of recurrence.Total
excision or intralesional excision or curettage must be done for the entire
cyst wall, all abnormal tissues that feel spongy and unhealthy, and bone
surfaces that are lined with the cyst membranes [3].
For big and destructive cysts, complete excision or extensive curettage will
most likely cause iatrogenic instability, requiring instrumented fusion of some
levels above and below, to maintain spinal stability in the post operative
rehabilitation and recovery period,Multidisciplinary team work showed a very rapid and good outcomes
in treating this patient, starting from the caring surgical team who received ,investigated
and operated upon the patient ,the diagnostic and interventional radiologist who
helped a lot in diagnosis and preparing the patient for surgery, making surgery
easier and less complicated, the nurses in the operating theater and caring for
the patient in the ward, the rehabilitation and physiotherapy team making good
and rapid recovery, and the histopathologist who confirmed the diagnosis .
CONCLUSION
Early diagnosis and appropriate surgical treatment of the
Aneurysmal Bone Cysts” ABCs “ in the spine remain the key factors to successful
management. Complete surgical excision or intralesional curettage and grafting of
ABC remain the best method to treat symptomatic patient with or without neurological
findings, and has the best short and long-term outcomes. Treating young
patients with ABC and neurological signs and symptoms should be aggressive and
should not be delayed for better outcome. Preoperative planning and
multidisciplinary teamwork will guarantee the best outcome.
Acknowledgements
None.
Conflict
of interest:
No
conflict of interest for publication of manuscript.
Funding:
Nothing
to disclose.
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