Upload
aakansha
View
228
Download
1
Embed Size (px)
Citation preview
ww.sciencedirect.com
med i c a l j o u r n a l a rm e d f o r c e s i n d i a x x x ( 2 0 1 3 ) 1e4
Available online at w
journal homepage: www.elsevier .com/locate/mjafi
Case Report
Vertebral intraosseous lipoma
Lt Col Debraj Sen a,*, Brig Lovleen Satija b, Col Samar Chatterji c, Anusree Majumder d,Meenu Singh e, Aakansha Gupta e
aClassified Specialist (Radiodiagnosis), Command Hospital (Central Command), Lucknow 226002, IndiabConsultant & Professor (Radiodiagnosis), Command Hospital (Central Command), Lucknow, IndiacAssociate Professor, Department of Radiodiagnosis, Armed Forces Medical College, Pune 40, IndiadResident (Pathology), Command Hospital (Eastern Command), Kolkata, IndiaeResident (Radiodiagnosis), Command Hospital (Central Command), Lucknow, India
a r t i c l e i n f o
Article history:
Received 19 December 2012
Accepted 1 May 2013
Available online xxx
Keywords:
Vertebra
Intraosseous
Lipoma
Computerized Tomography
Magnetic resonance imaging
* Corresponding author. Tel.: þ91 9670574817E-mail address: [email protected] (D
Please cite this article in press as: Sen D, edx.doi.org/10.1016/j.mjafi.2013.05.001
0377-1237/$ e see front matter ª 2013, Armhttp://dx.doi.org/10.1016/j.mjafi.2013.05.001
Introduction
Lipomatous tumours are ubiquitous and the commonest tu-
mours to affect soft tissues. Despite the fat content of bone
medulla, intra-osseous lipoma is the rarest primary tumour to
afflict bones.1 Here we present an unusual case of vertebral
intraosseous lipoma in a young male with low backache. This
article aims to discuss and highlight the radiological and
pathological features of this rare entity which may often be
missed or misinterpreted.
(mobile).. Sen).
t al., Vertebral intraosse
ed Forces Medical Service
Case report
A 35-year-old male patient presented with chronic low back-
acheofoneyearduration thatwas insidious inonset,moderate
in intensity and aggravated byprolonged standing. Thepatient
did not have radiculopathy or neurogenic claudication. There
wasnohistoryof anycomorbidcondition,medicationor spinal
trauma. The patient’s vital parameters were normal. Lower
paraspinal muscle spasm was noted. There was no point
tenderness, swelling, evidence of sacroiliitis or neurological
deficit. All laboratory investigations were normal.
Lateral radiograph of the lumbosacral spine showed an ill-
defined transradiant lesion in the superior part of L4 vertebral
body (Fig. 1). Computerized Tomography (CT) revealed a
sharply marginated ovoid intraosseous lesion of fat attenua-
tion (�70 Hounsfield Units) at the same location. The lesion
had a thin rim of sclerosis. A punctate calcific focus was noted
within the lesion (Fig. 2). The overlying endplate cortex was
thinned without any obvious disruption. Degenerative
changes in the form of marginal osteophytes and semilunar-
shaped areas of endplate sclerosis were present. Magnetic
Resonance Imaging (MRI) confirmed the CT findings and
revealed a lesion of fat intensity (hyperintense on both T1-
and T2-weighted images). A thin rim hypointense on both T1-
and T2-weighted images consistent with marginal sclerosis
was present. Disc desiccation and Modic changes were also
noted (Fig.3). There was no evidence of sacroiliitis. Based on
these findings a diagnosis of lumbar spondylosis with intra-
osseous lipoma of L4 vertebral body was made.
ous lipoma, Medical Journal Armed Forces India (2013), http://
s (AFMS). All rights reserved.
Fig. 1 e Lateral radiograph of the lumbosacral spine reveals
a subtle transradiant lesion (arrow) in the superior part of
the body of L4 vertebra.
me d i c a l j o u r n a l a rm e d f o r c e s i n d i a x x x ( 2 0 1 3 ) 1e42
Discussion
Fatty tumours affecting bones may be classified as: (a) soft-
tissue lipomata or liposarcomata with secondary bone
involvement; (b) parosteal lipomata, which arise from the
subperiosteal tissue; (c) intraosseous lipomata, which arise
from the medullary cavity; (d) liposarcoma of bone and (e)
liposclerosing myxofibrous tumour.2,3
Fig. 2 e The panel of axial, coronal and sagittal CT images revea
calcific focus in the body of L4 vertebra (arrow).
Please cite this article in press as: Sen D, et al., Vertebral intraossedx.doi.org/10.1016/j.mjafi.2013.05.001
First reported in 1880,4 intraosseous lipoma is the rarest
primary bone tumour with an incidence of 0.1%.3,5,6 However,
recent reports suggest a wider prevalence of up to 2.5%.3,6
Intraosseous lipoma is underreported for many reasons: (a)
non-specific radiographic appearances which may simulate
other entities, (b) benign radiographic appearances which
preclude further CT or MRI, (c) difficulty in histopathologic
interpretation if not correlated with radiology as fat in these
lesions may be indistinguishable from normal fat in yellow
marrow, and osteonecrosis if ischaemic changes are present.3
Intraosseous lipoma has been reported most frequently in
the 4th and 5th decades3,7 and is slightly more common in
males.7
Pain has been reported in up to 66% of cases.3 The aetiology
of pain is speculated to be due to expansile remodelling of
bone or co-existent intralesional ischaemic changes. Patho-
logical fractures occur rarely.1
Most of these tumours occur in the lower limb (71%). The
commonest site is the calcaneum (32%) followed by the
femoral sub-trochanteric region, proximal tibial and distal
femoral shaft and the proximal and distal fibular shaft.7 Upper
limb lesions usually involve the proximal and distal humeral
and radial shafts. They are usually intramedullary, rarely
intracortical and frequently eccentric in smaller long bones.
They have also been reported in the spine,8,9 skull and sino-
nasal cavities,10,11 mandible, pelvis and ribs.5 Multiple intra-
osseous lipomata affecting multiple bones have also been
reported.3,4 Lesion size varies from 10 to 120 mm (mean
39 mm).3,7
The aetiology and nature of intraosseous lipomas is
controversial. While some regard them as benign tumours of
the medullary adipose tissue, others consider them to be
reactive changes secondary to infarcts, infections, or the
result of healed bony infarcts secondary to trauma.12 An as-
sociation with hyperlipoproteinaemia1 and chromosomal
abnormalities has been reported.12 The increased prevalence
of intraosseous lipoma at sites with decreased trabecular
bone, like the calcaneus, has led to the theory that they
represent an ‘overshoot’ of haematopoietic to fatty marrow
conversion, and may therefore be considered hamartomas.3
At gross examination, intraosseous lipomas are pale or
bright yellow, may reveal lobulations with a thin capsule and
septations.3 They are composed of mature adult fat and may
contain a few atrophic trabeculae.
ls a well-delineated lesion of fat attenuation with a central
ous lipoma,Medical Journal Armed Forces India (2013), http://
Fig. 3 e Sagittal T2 e (a) and T1-weighted images (b) reveal a lesion of fat intensity in the body of L4 vertebra adjacent the
superior endplate (arrow). Also noted are disc desiccation and Modic type 2 endplate changes.
med i c a l j o u r n a l a rm e d f o r c e s i n d i a x x x ( 2 0 1 3 ) 1e4 3
Ascribing involutional changes to the histopathologic fea-
tures of intraosseous lipomata, Milgram subdivided them into
3 stages: Stage 1 lesions consist of viable adipocytes without
abnormal cytologic features (normal fat); Stage 2 lesions are
composed of viable adipocytes, fat necrosis and dystrophic
calcification; Stage 3 lesions exhibit extensive fat necrosis,
calcification, cyst formation, reactive peripheral or intrale-
sional ossification, with occasional viable adipocytes.3,12
There is no preponderance of stage 2 and 3 lesions with
advancing age.7 It is speculated that the enlargement of these
lesions in the confined space of the intramedullary canal rai-
ses the intramedullary pressure causing ischaemic fat ne-
crosis and calcification. An alternate theory propounds that
the calcification seen in these tumours might be a product of
the mesenchymal cells in the lesion.3 Stages 2 and 3 lesions
are thus most frequently confused with bone infarct
histologically.
The radiologic appearance of an intraosseous lipoma par-
allels its Milgram stage.3,6 On plain radiography, Milgram
stage 1 lesions are well-circumscribed, transradiant lesions
occasionally associated with mild focal expansile remodel-
ling. Bone expansion is more prominent in thin long bones
such as the fibula. Stage 1 lesion may simulate unicameral
bone cyst, aneurysmal bone cyst, fibrous dysplasia, and
plasmacytoma.3,6 Overall marginal sclerosis and calcification
are seen in 45% and 42% of lesions, respectively, however
these findings are more common in lesions located in the
calcaneum (61%).8 Bone expansion is noted in 33% of sites
Please cite this article in press as: Sen D, et al., Vertebral intraossedx.doi.org/10.1016/j.mjafi.2013.05.001
overall, but infrequently in the calcaneum (13%).7 CT dem-
onstrates the intralesional fat (�600HU to�100 HU), a thin rim
of sclerosis and, if present, expansile remodelling of the
intramedullary canal. On MRI, the intralesional fat appears
similar to subcutaneous fat. Normal yellow marrow shows
signal intensity lower than that of the intraosseous lipoma on
T1-weighted images, related to cellular elements. Fat can also
be demonstrated on MRI by fat suppression sequences.
Milgram stage 2 or 3 lesions appear as transradiant lesions
with central or ring-like calcification or ossification. The
ossification may be extensive, leading to the term ossifying
lipoma.3 A predominantly calcified or ossified lesion may
mimic an enostosis. Partially mineralized lesions may be
mistaken for chondroid lesions or osteonecrosis on radio-
graphs. On CT and MRI, intralesional fat (unless it is
completely calcified or ossified) distinguishes the intra-
osseous lipoma from tumours of chondroid, osteoid, or fibrous
origin. On MRI, calcification is seen as foci of low signal in-
tensity on both T1- and T2-weighted images. Intraosseous li-
poma may be difficult to differentiate from osteonecrosis at
MR imaging and CT because both lesions contain intrinsic fat
with a rim of tissue separating the lesion from surrounding
marrow. Expansile remodelling of bone, osteolysis, and a
rounded rather than irregular serpentine margin suggest an
intraosseous lipoma.
With progressive ischaemia and involution, fibrous prolif-
eration and cystic degeneration occurs in an intraosseous li-
poma (Milgram stage 3 lesions). This and a skeletal
ous lipoma, Medical Journal Armed Forces India (2013), http://
me d i c a l j o u r n a l a rm e d f o r c e s i n d i a x x x ( 2 0 1 3 ) 1e44
distribution similar to unicameral bone cysts in adults has led
to the postulation that unicameral bone cysts may represent
completely involuted intraosseous lipomas. On radiographs,
severely involuted lesions demonstrate a thick peripheral rind
of ossification with variable amounts of central ossification-
calcification producing a distinctive ‘bull’s-eye’ appearance.
Despite the heterogeneous appearance of a severely involuted
intraosseous lipoma on both CT and MR images, the identifi-
cation of intralesional fat permits a definitive diagnosis.
Bone scintigraphy of intraosseous lipomas demonstrates
radionuclide uptake ranging from absent to moderate.3
Intraosseous lipoma in the vertebra may occasionally
mimic haemangioma and osteoporotic bone with increased
fatty marrow.8 Abnormal biomechanical stress due to end-
plate cortical thinning as in our case may be a contributor to
backache and it may be worthwhile to carefully look for these
lesions.
Conclusion
Intraosseous lipoma is the rarest primary bone tumour that
often poses a diagnostic dilemma on plain radiography
because it may be confused with a bone infarct, chondroid
neoplasm, fibrous dysplasia, or other benign conditions. CT
and MRI are helpful in diagnosis by elucidating intralesional
fat.
Conflicts of interest
All authors have none to declare.
Please cite this article in press as: Sen D, et al., Vertebral intraossedx.doi.org/10.1016/j.mjafi.2013.05.001
r e f e r e n c e s
1. Radl R, Leithner A, Machacek F, et al. Intraosseous lipoma:retrospective analysis of 29 patients. Int Orthopaedics.2004;28:374e378.
2. Hart JAL. Intraosseous lipoma. J Bone Jt Surg. 1973;55B:624e632.
3. Murphey MD, Carroll JF, Flemming DJ, Pope TL, Gannon FH,Kransdorf MJ. From the archives of the AFIP. Benignmusculoskeletal lipomatous lesions. RadioGraphics.2004;24:1433e1466.
4. Rehani B, Wissman R. Multiple intraosseous lipomatosis: acase report. Cases J. 2009;2:7399.
5. Palczewski P, �Swiatkowski J, Gołebiowski M, Błasi�nska-Przerwa K. Intraosseous lipomas: a report of six cases and areview of literature. Pol J Radiol. 2011;76:52e59.
6. Propeck T, Bullard MA, Lin J, Doi K, Martel W. Radiologic-pathologic correlation of intraosseous lipomas. Am JRoentgenol. 2000;175:673e678.
7. Campbell RSD, Grainger AJ, Mangham DC, Beggs I, Teh J,Davies AM. Intraosseous lipoma: report of 35 new cases and areview of the literature. Skeletal Radiol. 2003;32:209e222.
8. Pande KC, Ceccherini AFA, Webb JK, Preston BJ. Intraosseouslipomata of adjacent vertebral bodies. Eur Spine J.1998;7:344e347.
9. Kim JT, Han YM, Chung DS, Park YS. Intraosseous lipoma ofthe lumbar spine. J Korean Neurosurg Soc. 2004;35:220e222.
10. Taheri MS, Pourghorban R, Nassab MS, Pourghorban R.Sphenoclival intraosseous lipoma in skull base. OpenNeuroimaging J. 2012;6:99e102.
11. Abdalla WMA, da Motta ACBS, Lin SY, McCarthy EF,Zinreich SJ. Intraosseous lipoma of the left frontoethmoidalsinuses and nasal cavity. Am J Neuroradiol. 2007;28:615e617.
12. Eyzaguirre E, Liqiang W, Karla GM, Kumar R, Alberto A,Gatalica Z. Intraosseous lipoma. A clinical, radiologic, andpathologic study of 5 cases. Ann Diagn Pathol. 2007;11:320e325.
ous lipoma,Medical Journal Armed Forces India (2013), http://