Keywords
aneurysmal bone cyst - vascular tumor - pregnancy - pathological fracture - spinal
cord compression
Introduction
The World Health Organization defined aneurysmal bone cyst (ABC) as “an expanding
lesion with blood-filled cavities, separated by septa of trabecular bone or fibrous
tissue-containing osteoclast giant cells.”[1] It is usually found in the long bones and develops before the second decade of life.[2] Incidence of spinal ABC is 15% of all primary spine tumors.[1] Association of ABC with pregnancy is a very rare entity.[2] It may enlarge during pregnancy.[2] We are reporting a unique case of aneurysmal bone cyst of L2 vertebra, presenting
as pathological fracture, paraplegia, and retroperitoneal mass during pregnancy.
Case Report
A 26-year-old pregnant (28 week) female patient was admitted in the obstetrics department
with paraplegia with fetal distress. She had a history of low backache for 10 days.
Immediately a premature baby was delivered by cesarean section. She was referred to
the neurosurgery department for further evaluation. On examination, hypotonia was
present in both the lower limbs. Power in both lower limbs were 0/5 (the Medical Research
Council grade) at the hips, knee, ankles, and great toe for all movements. Superficial
abdominal reflexes were present. Plantar reflexes were bilaterally mute. There was
a 20% sensory deficit below L1 level bilaterally for all modalities. There was no
bowel, bladder disturbances.
Computed tomography scan lumbosacral (LS) spine showed an L2 vertebral body fracture
with a left paraspinal mass, involving L2 vertebra ([Fig. 1A1–A3]) and magnetic resonance imaging (MRI) showed large expansile multiloculated lesion,
with retroperitoneal extension with fluid–fluid levels with L2 vertebral body fracture
suggestive of aneurysmal bone cyst ([Fig. 2A1–A3]). After discussion of risk factors with relatives, surgery was planned. Preoperative
embolization was done with polyvinyl aspartate particles (150–200 µm) one day before
surgery. L1, L2 laminectomy, removal of intraspinal portion of ABC ([Fig. 3A, B]) and D12 to L3 pedicle screw fixation was done. After 1 month, complete excision
of retroperitoneal part was done, with the help of the general surgeon's team, through
transabdominal approach. The histopathological examination had confirmed ABC ([Fig. 4A, B]). Immunohistochemistry was estrogen and progesterone receptor negative (ER/PR) and
Her-2/neu negative. Postoperative X-ray LS spine showed pedicle screw in situ ([Fig. 1B1, B2]). Postoperative MRI showed residual ABC after the first surgery ([Fig. 2B1–B3]) and complete excision of ABC after second surgery ([Fig. 2C1–C3]). Postoperative period was uneventful with significant recovery. At 3 months follow-up,
power was 4/5 at the hips, knee, and great toe and 3/5 at the ankle. There were no
sensory deficit and no bowel, bladder disturbance. The patient was able to walk with
support. As the gestational effect could not be predicted, she was advised against
next pregnancy. Relatives were explained the need of radiotherapy, if recur.
Fig. 1 (A) Preoperative CT scan LS spine (A1: axial, A2: coronal, A3: sagittal with 3D reconstruction)
showing L2 vertebral body fracture with a left paraspinal mass (B1, B2). (B) Postoperative
X-ray LS spine (B1: anteroposterior, B2: lateral view) showing pedicle screw in situ.
CT, computed tomographic; LS, lumbosacral.
Fig. 2 MRI DL spine. (A) Preoperative (A1: sagittal, A2: coronal, A3: axial section) showing
large expansile multiloculated lesion, with retroperitoneal extension with fluid–fluid
levels with L2 vertebral body fracture. (B) Postoperative after first surgery (B1:
sagittal, B2: coronal, B3: axial section) showing residual ABC. (C) After second surgery
(C1: sagittal, C2: coronal, C3: axial section) showing complete removal of ABC. DL,
degenerative lumbar; MRI, magnetic resonance imaging.
Fig. 3 (A, B) Intraoperative photograph showing posterior decompression.
Fig. 4 Microphotographs of histopathological examination (hematoxylin & eosin staining (A)
×10 and (B) ×40) multiple blood-filled lacunae, separated by collagenous tissue containing
spindle-shaped fibroblasts, dilated capillaries, and osteoclastic giant cells, with
no endothelial lining.
Discussion
ABCs can occur as primary (70%) or secondary (30%) lesion.[3] Primary ABC is considered as neoplasm, driven by upregulation of the ubiquitin specific
protease USP6 (Tre2) gene.[3] Secondary ABCs are associated with other lesions. Pathogenesis of enlargement of
ABC during pregnancy is not clear.[2] According to Webber et al, ABCs associated with pregnancy might be primary neoplasm
as USP 6 positive.[4] However, it also consists of reactive component explained on the basis of the presence
of insulin-like growth factor-1 (IGF-1) receptor expression.[4]
Few cases of the ABCs are reported with pregnancy[2]
[4]
[5]
[6]
[7]
[8]
[9]
[10] ([Table 1]). Change in symptomatology can be due to hormonal changes during pregnancy.[2]
[4]
[7]
[9] Cataltepe et al proposed hormonal changes, such as increased hematopoietic activity,
increased cortisone, with vitamin D antagonistic effect, and human placental lactogen
with growth hormone-like effect as a causative factor in pregnancy.[2] Webber et al suggested increased IGF-1, involved in bone remodeling and repair,
as a causative factor during pregnancy.[4] Amanatullah et al suggested role of circulating growth hormone in pregnancy, along
with transforming growth receptor—β receptors on cells of ABC.[9] Progesterone and estrogen levels increase during pregnancy and causes venous distension
and vascular growth, respectively, which can increase local venous pressure. Parathyroid
hormone-related protein also increases during pregnancy and can cause osteoporosis
and pathological fracture. Human placental growth factors (HPlGF), which are involved
in bone remodeling and repair, can be a causative factor in pregnancy. In the present
case of ABC, staining for ER, PR, and Her-2/neu were negative. In three cases, reported
by Webber et al,[9] staining for ER, PR, and HPlGF were negative, but positive for IGF-1.[4]
Table 1
Reported cases of aneurysmal bone cyst during pregnancy
|
Serial number
|
Author
|
Year
|
Number of cases
|
Site
|
Primary vs. secondary
|
|
1
|
Baker et al[5]
|
1982
|
1
|
Ethmoid
|
Primary
|
|
2
|
Issa et al[6]
|
1986
|
1
|
Right ilium
|
Primary
|
|
3
|
Mintz et al[7]
|
1987
|
1
|
Right humerus and acromian process of left scapula[a]
|
Secondary
|
|
4
|
Cataltepe et al[2]
|
1990
|
1
|
Frontal bone
|
Primary
|
|
5
|
Webber et al[4]
|
2011
|
3
|
Femur
|
Primary
|
|
Scapula
|
Primary
|
|
Humerus
|
Primary
|
|
6
|
Westbury et al[8]
|
2011
|
1
|
Mandible
|
Secondary
|
|
7
|
Amanatullah et al[9]
|
2012
|
1
|
Humerus
|
Primary
|
|
8
|
Elkattah et al[10]
|
2013
|
1
|
Left ilium
|
Primary
|
|
9
|
Present case
|
2014
|
1
|
Lumbar spine
|
Primary
|
a Aneurysmal bone cyst at two sites in single patient.
Gravid uterus increases the pressure in paravertebral veins by compressing the vena
cava, which causes hemorrhage and osteolysis, further leading to hemorrhage and amplification
of ABCs.
Management of ABC in third trimester includes cesarean section, followed by spine
fixation. Expulsive forces of labor could predispose to life-threatening uncontrolled
bleeding. Total excision is the treatment of choice, if feasible. Curettage and bone
grafting are the standard treatment for the central spinal ABCs. If there is vertebral
body involvement, combined anterior and posterior approaches for tumor removal and
fusion are required to maintain the structural integrity.
Radiotherapy is helpful to diminish the blood supply of the tumor when complete surgical
excision is not possible. Recent studies showed that denosumab, a human monoclonal
antibody can treat ABCs.[4] In the future, denosumab can play a major role in treatment policies.
Prognosis is good, even after recurrence. Recurrence after surgery is related to the
cavities not been fully opened. A residual small cyst with radiolucency is of concern
and requires regular follow-up. Aneurysmal bone cyst can increase in size during pregnancy.
Timely diagnosis can avoid complications.
