Skeletal Radiol (2014) 43:423–436 DOI 10.1007/s00256-013-1792-3
REVIEW ARTICLE
Paediatric acquired pathological vertebral collapse Hassan Hirji & Asif Saifuddin
Received: 24 July 2013 / Revised: 28 October 2013 / Accepted: 26 November 2013 / Published online: 9 January 2014 # ISS 2014
Abstract Vertebral collapse is a significant event in the paediatric patient with a real potential for associated deformity and morbidity. While in adults the causes tend towards the malignant, particularly metastatic and metabolic disease, the paediatric population demonstrates a different range of diagnoses. This article reviews the typical imaging findings of the more common underlying acquired pathological causes of vertebral collapse in children, including Langerhans cell histiocytosis, chronic recurrent multifocal osteomyelitis, osteogenesis imperfecta. Other causes include pyogenic osteomyelitis and tuberculosis and neoplastic lesions, either primary, metastatic or of haematological origin. Keywords Spinal diseases . Spinal neoplasms . Paediatric acquired pathological vertebral collapse
Introduction Vertebral collapse is an extremely rare, but significant event in the paediatric patient, with a real potential for associated pain, deformity and morbidity. While in adults the causes tend towards the malignant, particularly metastatic and metabolic disease, in the paediatric population a different range of differential diagnoses is encountered, reflecting the nature of the
A. Saifuddin (*) Royal National Orthopaedic Hospital, Stanmore, UK e-mail: [email protected] H. Hirji North West London Hospitals NHS Trust Northwick Park Hospital, Harrow, UK
developing spine with a higher preponderance of primary lesions. Furthermore, the natural on-going growth of the paediatric spine may permit good recovery even with conservative management. This article seeks to provide a review of the typical imaging findings of the more common underlying acquired pathological causes of vertebral collapse in children. Collapse secondary to trauma has not been included, nor have diseases of a congenital origin.
Anatomy and normal imaging appearances As in the adult, the spine consists of bony vertebrae separated by compressible intervertebral discs. The vertebrae have large bodies that consist of a dense outer bony cortex and contain the highly vascular marrow. Unlike the adult spine, the soft tissues are more flexible and the age-related changes of osteopenia and disc degeneration are less frequent, if at all present. The vertebral end plates are not fused, giving the spine the possibility of remodelling with restoration of almost normal height, even following quite severe and deforming disease. The arterial supply to the vertebral body is through periosteal branches, which penetrate the vertebral body at several sites adjacent to each endplate, and the lumbar artery. In addition, there are posterior arterial branches that pass across the posterior border of the vertebral body and anastomose near the midline [1, 2]. These are important to recognise as inflammatory and vasculitic processes will be predisposed to arise near the arterial vessels, increasing the destructive effects at these sites. The venous drainage is through small tributary vessels that pass through the medulla to a central venous channel, the basivertebral vein, which drains from the dorsal aspect of the vertebral body. Here it merges with a large valveless
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venous plexus, which allows the ready passage of infection and metastatic seeding, particularly from the pelvis or perineum [1, 3]. At birth, the marrow space is filled with red (haematopoietic) marrow. Over the first 5 years, this undergoes gradual conversion to yellow marrow. On MRI, red marrow has T1W signal intensity (SI) greater than muscle, but less than fat. As the child moves towards maturity, the red marrow is replaced by fatty, yellow marrow. This has a shorter T1 relaxation time giving a higher T1W signal and a lower T2W signal. A more detailed description of marrow signal in
Fig. 1 Pyogenic osteomyelitis in a 14-year-old girl. a Lateral radiograph of the thoraco-lumbar spine showing erosion of the anterior–superior corner of the L1 vertebra (arrow). b Sagittal T1-weighted spin echo (T1W SE) and c T2-weighted fast spin echo (T2W FSE) MR images showing end-plate erosion, loss of disc height and extensive marrow oedema-like signal intensity (SI; arrows) with minor anterior sub-ligamentous spread of infection. d Sagittal post-contrast fat-suppressed T1W SE MR image showing enhancement of the anterior soft tissue extension (arrow) and also focal disc enhancement. e Sagittal CT multiplanar reconstruction (MPR) showing end-plate erosions and medullary sclerosis (arrows) consistent with the relatively chronic nature of the disease process. f Sagittal short T1 inversion recovery (STIR) MR image shows normalisation of the marrow SI within T12 and L1, indicating healing with complete loss of the intervening disc
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children and its changes with maturation has been provided by Foster et al [4].
Imaging technique As with the adult spine, AP and lateral radiographs should first be obtained, with standing radiographs, if possible, depending upon the level of pain, allowing an assessment of overall spinal alignment. Following radiography, MRI will invariably be the next investigation, and the majority of cases can be
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Fig. 2 Pyogenic L2–L3 discitis in a 13-year-old boy. a Sagittal T1W SE, b sagittal STIR and c)axial T2W FSE MR images showing destruction of the disc, mild end-plate oedema and prominent posterior extension of the phlegmon deep to the posterior longitudinal ligament (PLL; arrows)
adequately diagnosed purely on this combination of imaging. In the setting of vertebral collapse, CT and scintigraphy add little further diagnostic information. The MRI technique for assessing the paediatric spine does not differ from the adult spine, typically comprising a combination of sagittal and axial T1W spin echo (SE) and T2W FSE sequences. The addition of a fat-suppressed sequence (STIR or fat-suppressed T2W FSE) is of value in the assessment of suspected neoplastic, infective or inflammatory disorders and imaging of the whole spine should always be performed to look for multilevel non-contiguous disease, both for the Fig. 3 Tuberculosis (TB) osteomyelitis of T3 in a 10-yearold girl. a Lateral plain radiograph of the thoracic spine shows marked anterior collapse and wedging of T3 (arrow) with focal kyphosis. b Sagittal T1W SE MR image shows associated anterior and posterior sub-ligamentous spread of infection with mild spinal cord compression (arrows)
purpose of overall disease staging, but also to aid in differential diagnosis. As in the adult spine, the administration of IV gadolinium is of particular value in suspected spinal osteomyelitis/discitis to aid in the differentiation of phlegmon from abscess. Depending upon the age of the child and/or the level of pain, general anaesthesia may be required. Diffusionweighted imaging may be misleading since increased marrow SI may be seen in 48 % of normal children [5]. If required, staging of the remainder of the skeleton can be achieved with whole-body bone scintigraphy, or for some conditions, such as suspected Langerhans’ cell histiocytosis
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(LCH), with radiographic skeletal survey. However, wholebody MRI using a combination of coronal T1W SE and STIR sequences is now becoming commonplace [6–8] When a diagnosis cannot be achieved based on clinical and imaging features alone, then consideration will have to be given to percutaneous needle biopsy, which is safely performed with CT guidance under general anaesthesia [9]
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the outer cortex and the integrity of the trabecular bone and marrow within. Diseases causing destruction of either of these components may lead to a loss of vertebral height. Vertebra plana occurs when the vertebral body is reduced to a single dense sclerotic band, often with preservation of the discs on either side.
Differentiating from trauma Acquired paediatric vertebral collapse Vertebral collapse occurs secondary to a failure in the mechanical integrity of the anterior and/or middle columns of the vertebral body. The vertebral body derives its strength from Fig. 4 TB osteomyelitis of the lumbo-sacral junction in a 16-year-old boy. a Sagittal T1W SE and b T2W FSE MR images showing diffuse marrow oedema-like SI in the L5, S1, S2 and S3 vertebrae. Note the absence of disc involvement and the extensive anterior subligamentous extension (arrows). c Coronal T2W FSE MR image showing a large left psoas abscess (arrows). d Axial T2W FSE MR image showing extension into the neural arch (arrows) as well as the large anterior sub-ligamentous collection
It can be difficult to differentiate between a pathological fracture and a post-traumatic injury, but this can be of vital importance in determining further care and future prognosis. Traumatic injuries have a preponderance in the cervical spine of young children and for the thoracolumbar spine in older
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children and teenagers [10]. The differentiation between a vertebral fracture due to trauma and one caused by pathological collapse will clearly depend upon the history of a significant injury, as well as the imaging features. Simple vertebral fractures with no underlying cause will have the same imaging features as wedge and burst fractures in adults. Features suggestive of simple trauma include marrow oedema involving mainly the upper aspect of the vertebral body with some residual fatty marrow, relative sparing of the pedicles, retropulsion of the posterior superior cortex and the absence of a surrounding soft tissue mass. The relative prevalence of the different causes of acquired paediatric vertebral collapse is difficult to determine, since it will be highly dependent upon the specialist nature of the treating centre. Our experience is in the setting of a tertiary referral spinal orthopaedic setting, in which case chronic recurrent multifocal osteomyelitis (CRMO) is anecdotally the commonest cause.
Infective causes
Fig. 5 Ewing sarcoma of C4 in a 15-year-old boy. Lateral radiograph showing lytic collapse of C4 with mild focal kyphosis (arrow)
Pyogenic osteomyelitis Pyogenic osteomyelitis is an uncommon presentation of bone infection, which may be due to almost any infectious pathogen. The most common agent is Staphylococcus sp., but other common organisms include H. influenza, Salmonella sp., E. coli and Neisseria gonorrhoeae. The infection classically reaches the spine via haematogenous spread within the venous plexus, although direct inoculation, such as accidental exposure during surgery is also seen. Sites of infection are classically in the lumbar spine, with the cervical and thoracic vertebrae less commonly affected. Unlike adults, in which the vertebral end plate is closed, the end plate allows the passage of infection through to the adjacent disc space. As such, infection may be seen to pass from an affected vertebral body to a contiguous vertebral body. Plain radiographs may show a reduction in vertebral body height. The preponderance is for anterior vertebral body involvement (Fig. 1a). MRI shows variable fluid within the disc space, which may show loss of height, erosion of the endplates and extensive marrow oedema-like SI within the adjacent vertebral bodies (Fig. 1b, c). Disc and vertebral enhancement will be seen following contrast agent administration (Fig. 1d). Depending upon the chronicity of the lesion, there may also be associated sub-chondral marrow sclerosis, best appreciated with CT (Fig. 1e). With adequate antibiotic therapy, marrow SI will return to normal (Fig. 1f). Other characteristic features of pyogenic discitis include epidural extension deep to the posterior longitudinal ligament (PLL; Fig. 2).
Tuberculous osteomyelitis Tuberculous infection of the spine (Pott’s disease) is an uncommon manifestation of tuberculosis (TB), but where the skeleton is affected, roughly half will have spinal disease [11]. It is most commonly seen in children in endemic areas. Classically occurring through haematogenous spread, the origin is frequently unknown, but approximately 50 % of children will have co-existing pulmonary involvement.
Fig. 6 Aneurysmal bone cyst (ABC) in a young boy. Antero-posterior (AP) radiograph of the lumbar spine showing collapse of the left side of the L3 vertebral body (arrows) with absence of the left pedicle
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characteristic feature of tuberculosis (Fig. 4d) [12, 13]. TB may also produce vertebra plana [9]. Diffusionweighted imaging has been found to have poor specificity (66 %) at distinguishing between tuberculosis and pyogenic osteomyelitis [14]
Infection typically affects the anterior vertebral endplate with granulomatous disease predominating in the early phase. Expansion of the lesion destroys the trabeculae and may lead to anterior collapse and subsequent wedging. Infective foci can erode through the cortex to form sub-ligamentous and soft-tissue abscesses. Kyphosis due to anterior wedging is a common feature (Fig. 3) [11]. The thoracic spine is the most common site of disease, followed by the lumbar and cervical spine. The disease is normally contiguous, but can occur at multiple noncontiguous levels, necessitating routine MR imaging of the whole spine [8, 9]. Tuberculous lesions show low SI on T1W imaging (Fig. 4a) and appear hyperintense on T2W (Fig. 4b) and STIR sequences. Unlike other forms of discitis, disc space narrowing is uncommon and preservation aids diagnosis (Fig. 4a, b). Involved discs may show increased signal on T2W sequences, which can be difficult to identify in the paediatric spine where the discs have a naturally high signal. Differentiating between tuberculous and pyogenic infections is aided by peripheral enhancement with gadolinium in TB, as opposed to more diffuse enhancement in pyogenic infection. Other classical features include large anterior sub-ligamentous and psoas abscesses (Fig. 4c, d). Furthermore, infection involving the posterior elements is a
Ewing sarcoma is the second most common malignant primary spinal tumour in children, peaking at the age of 15 years and commonly presenting with a combination of pain and neurological deficit. The tumour typically arises unilaterally in the neural arch with secondary involvement of the vertebral body [16]. A large extra-osseous mass is usually seen at the time of presentation, which may impinge on the canal causing neurological symptoms. Imaging features are of an expansile
Fig. 7 ABC of L2 in a 17-year-old girl. a AP radiograph shows lytic collapse of the left side of the L2 vertebral body with absence of the left pedicle (arrow) and a right thoraco-lumbar scoliosis. b Axial CT image showing the extensive vertebral destruction and the thinned expanded residual vertebral and neural arch cortex (arrows). c Corresponding axial
T1W SE MR image shows a lesion with heterogeneous internal SI characteristics (arrows). d Axial T2W FSE MR image demonstrates a low SI rim (arrows) and multiple fluid–fluid levels (arrowheads). e Axial post-contrast T1W SE MR image shows subtle septal enhancement throughout the lesion
Neoplastic causes Primary vertebral tumours are rare in children, with only one study demonstrating 8 affected children out of 1,971 cases of musculoskeletal tumours [15]. Nevertheless, it is important to recognise this group, as management is dependent on appropriate diagnosis and referral. Ewing sarcoma
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lesion with cortical thickening and destruction, which is predominantly lytic, with a minority showing a mixed appearance. In rare cases the tumour may arise within the vertebral body itself (Fig. 5). Tumour extension into the spinal canal is common with up to 91 % affected in some series [16, 17]. Metastases are to the lungs, bones and regional lymph nodes, often at the time of diagnosis [18]. Aneurysmal bone cyst Aneurysmal bone cysts (ABC) of the spine are benign, slowly growing, highly vascular lesions that predominantly affect the posterior elements unilaterally, but commonly extend into the vertebral body, where they may cause partial collapse or even vertebra plana [19]. ABCs may be primary in origin or secondary to other lesions such as osteoblastoma, giant cell tumour, chondroblastoma or fibrous dysplasia. They are twice as common in female subjects and usually present in the second decade of life. They are the second most common vertebral neoplasm [19]. Radiographs classically demonstrate a lytic lesion producing asymmetrical vertebral collapse
Fig. 8 Polyostotic fibrous dysplasia of the spine in a 13 year-old girl. a AP radiograph of the thoraco-lumbar junction, which shows collapse of the mildly sclerotic T11 vertebral body. Note also the involvement of the adjacent left 11th rib (arrows). b Axial and c sagittal CT MPR showing medullary sclerosis due to the ground glass matrix (arrows). A further lesion is seen in the inferior aspect of L1, which shows the classical thick sclerotic margin (short arrow), the “rind sign”
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owing to extension of the lesion from the neural arch into one side of the vertebral body, the absence of the ipsilateral pedicle being a classical feature (Fig. 6). The degree of collapse may be enough to produce a structural scoliosis (Fig. 7a). CT may show an “egg-shell” appearance of thinned expanded vertebral cortex (Fig. 7b). MRI demonstrates a characteristic, multi-loculated lesion with heterogeneous internal SI on T1W (Fig. 7c). A surrounding low SI rim may be evident on T2W sequences (Fig. 7d), which also classically demonstrate multiple fluid–fluid levels (Fig. 7d), representing sedimentation of blood products from recurrent haemorrhage within the cysts. Enhancing septae may be seen separating the fluid-filled cavities (Fig. 7e) [19]. Neurological compromise and cord compression have been associated with these lesions [20]. Fibrous dysplasia Fibrous dysplasia of the spine may be monostotic or polyostotic and can be seen as part of syndromes such as
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McCune–Albright. It most commonly affects the thoracolumbar region [21]. Spinal deformity is typically associated with the polyostotic form, which will also affect other parts of the skeleton [22]. In particular, involvement of the adjacent rib is a relatively common feature, which should suggest the diagnosis (Fig. 8a). The monostotic form is extremely rare and not commonly associated with collapse [21, 23]. Plain radiographs demonstrate a ground glass appearance, which may involve both the vertebral body and the posterior elements, and is optimally demonstrated on CT (Fig. 8b, c). Focal lesions may have a thick sclerotic margin, the “rindsign” (Fig. 8c). MRI shows reduced SI on both T1- and T2weighted sequences representing the fibrous component, or areas of fluid SI when there is associated cystic degeneration. Technetium 99 m MDP bone scan will normally demonstrate increased uptake in the affected regions of the bone [21, 23–25]. Osteosarcoma Osteosarcoma may develop as a primary lesion or secondary to spinal irradiation. Primary osteosarcoma is the most
Fig. 9 Osteosarcoma of T12 in a 16-year-old boy. a Coronal CT MPR shows lytic destruction and collapse of the right side of the vertebral body with a small paravertebral soft tissue mass (arrows). b Sagittal T2W FSE and c axial T1W SE MR images demonstrate diffuse vertebral marrow infiltration, pathological collapse and extra-osseous extension causing compression of the conus
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common primary malignant tumour of the spine in adults (excluding myeloma) and the eighth in children, with cases reported in children aged as young as 8 years [26]. The lesion typically involves the posterior elements, extending secondarily into the posterior vertebral body causing collapse, although less typically the lesion may be confined to the posterior body alone. Radiography and CT will frequently demonstrate mineralised matrix secondary to the deposition of osteoid. This may be extensive, producing an “ivory vertebra” appearance. In approximately 20 % of cases, the process may appear purely lytic (Fig. 9a). Extension into the vertebral canal is a common feature (Fig. 9b, c) [27]. Acute lymphoblastic leukaemia/lymphoma Acute lymphoblastic leukaemia/lymphoma (ALL) is a very rare cause of spinal collapse. Analysis by Meehan et al. found only 16 cases among 615 patients with leukaemia [28, 29]. This is most commonly seen in children under 5 years old, although cases are seen up to the second decade. Features of ALL include osteopenia, which can result in vertebral collapse in the absence of malignant marrow infiltration, and therefore
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Fig. 10 B-cell lymphoma in a 14-year-old boy. a Lateral radiograph of the lumbar spine showing diffuse osteopenia and mild collapse of T12 (arrow). b Sagittal T1W SE MR image of the cervico-thoracic spine showing mildly hyperintense intervertebral discs indicative of diffuse vertebral marrow infiltration and multilevel vertebral collapse (arrows). c Coronal STIR MR image of the sacrum showing diffuse marrow hyperintensity
Fig. 11 Osteosarcoma metastasis of L3 in a 17-year-old boy. a Lateral radiograph showing diffuse osteopenia mild anterior wedging of the L3 vertebra (arrow). b Sagittal T1W SE and c axial T2W FSE MR images demonstrate a hypointense metastasis in the anterior half of the vertebral body (arrows)
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no evident SI change in the vertebral bodies on MRI, while marrow involvement results in diffuse, homogenously low T1W and increased STIR SI 30–32]. There may be restoration of normal vertebral height through bone remodelling following treatment [32]. Similar appearances will be seen in childhood lymphoma (Fig. 10). Paediatric lymphoma may be primary or secondary. Primary lymphoma accounts for approximately 2–6 % of primary bone tumours in children, but more typically involves the long bones. Secondary lymphoma is more commonly nonHodgkins than Hodgkins (20 % vs 1–5 %) [33, 34]. Lymphoma may produce sclerotic or lytic lesions that may involve the whole vertebra and may have low T1W SI on MRI with a variable appearance on T2W [35–37]. Metastases Metastatic disease is less common in the paediatric population than in adults and has a different range of primary lesions, the most common being Ewing sarcoma and neuroblastoma, osteosarcoma, rhabdomyosarcoma, Hodgkin's disease, soft tissue sarcoma and germ cell tumour. [38] Vertebral metastases in children may derive from primary bone or soft tissue tumours. Secondary deposits from primary spinal bone tumours are also well recognised with Ewing sarcoma among the most common. These are associated with a poorer prognosis [39]. Metastases from extraosseous primaries include neuroblastoma and astrocytoma. Metastases are typically of low signal on T1W sequences replacing normal marrow and can be variable on T2 and STIR sequences [40] (Fig. 11). Whole-body MRI has been
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shown to have greater sensitivity than conventional imaging for bony metastases [7].
Miscellaneous causes Metabolic cause: idiopathic osteoporosis Idiopathic osteoporosis is a rare condition that most commonly presents in pre-pubescent children. It is characterised by bone demineralisation, but patients can be biochemically normal. Clinical features include pain in the spine and limbs, gait disturbance and muscle weakness. Radiographs demonstrate osteopaenia and may show vertebral collapse at multiple levels (Fig. 12). Metaphyseal compression in long bones has also been described and DEXA imaging will typically show
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Fig. 12 Idiopathic osteoporosis in a 16-year-old boy. a Lateral radiograph of the lumbar spine showing generalised osteopaenia and severe multilevel vertebral collapse (arrows). b Sagittal T2W FSE MR image demonstrates multilevel vertebral collapse with biconcave end-plates and secondary expansion of the intervertebral discs
Fig. 13 Langerhans cell histiocytosis (LCH). A 14-year-old boy with biopsy-proven LCH of C7. a Lateral cervical spine radiograph showing irregular, lytic vertebral collapse with anterior wedging and focal kyphosis. b Follow-up lateral radiograph shows progression to the vertebra plana. c Sagittal T1W SE and d T2W FSE MR images showing reduced T1W and increased T2W marrow SI. Note the maintenance of the cortical signal void of the C7 vertebral end-plates, the preservation of the adjacent discs and the extra-osseous extension (arrows)
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Fig. 14 Chronic recurrent multifocal osteomyelitis (CRMO). a Lateral radiograph of the thoracic spine in an 11-year-old girl showing collapse of the T8 vertebra (arrow). b Lateral radiograph of the thoracic spine in a 16year-old girl showing collapse of the T9 vertebra with marked loss of
vertebral height and diffuse medullary sclerosis (arrow). c Axial CT in the same patient as in b confirms the medullary sclerosis in the vertebral body with extension into both pedicles
reduced Z scores [41]. It is a disease of exclusion once other metabolic and genetic causes have been ruled out. Prevention of further vertebral fractures is the key to management, as the condition typically resolves spontaneously with time [42].
elements and may cause anterior wedging (Fig. 13a) [43]. It is one of the leading causes of pathological vertebral collapse in children, which may be so pronounced as to cause a vertebra plana (Fig. 13b). The disc spaces on either side of the collapsed vertebra are normally preserved, a feature seen clearly on MRI. Resolution of the disease can lead to restoration of vertebral body height [44]. Lesions are lytic and poorly defined on radiography and CT. MRI shows reduced marrow SI on T1W (Fig. 13c), increased SI on T2W (Fig. 13d) and STIR, and avid enhancement with gadolinium representing the hypervascular healing process. The T2/STIR hyperintensity
Langerhans cell histiocytosis Langerhans cell histiocytosis (LCH) produces eosinophilic granulomata within bone. These may be solitary or multiple, as in Hand–Schüller–Christian and Letterer–Siwe disease and may involve the spine. It is more common in male subjects and in particular in children under 5 years of age. The disease characteristically affects the vertebral bodies, often singly, but sometimes at multiple levels, typically sparing the posterior
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Fig. 15 CRMO in a 16-year-old girl. a Sagittal T1W SE and b T2W FSE MR images showing severe collapse at the T9 level with marrow sclerosis (same case as in Fig. 2b and c), but also multilevel involvement manifest by the presence of oedema-like marrow SI (arrows). Note the absence of any soft-tissue extension
Fig. 16 CRMO in an 11-year-old girl. a Sagittal T1W SE and b T2W FSE MR images showing moderate collapse at the T8 level with mild reduction of marrow SI and bulging of the posterior vertebral body cortex (same case as in Fig. 2a), but also multilevel involvement manifest by the presence of end-plate collapse and fatty marrow SI (arrows) indicating healed lesions
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Fig. 17 CRMO in an 11-year-old girl. Sagittal T2W FSE MR image showing multilevel mid-thoracic involvement with severe collapse of T6 resulting in marked focal kyphosis
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confined to the vertebral body or may extend into the posterior elements. MRI shows altered marrow signal with reduced SI on T1W sequences (Fig. 15a). T2W hyperintensity is seen in acute disease (Fig. 15b). Typically, changes are confined to one or more vertebrae without crossing the adjacent discs or contiguous vertebrae, a feature that differentiates from bacterial osteomyelitis. Vertebral collapse may lead to vertebra plana, but unlike LCH, this does not recover following treatment [48–51]. The absence of extra-osseous extension also aids in differentiation from LCH. Healed lesions show a variable degree of collapse, but normal marrow SI, although the marrow may become hyperintense on T1W owing to the replacement of red marrow with yellow marrow (Fig. 16). Depending upon the degree of collapse, significant kyphosis can develop (Fig. 17) [51]. Multilevel disease is not uncommon, and the finding that healed lesions manifest by mild vertebral collapse and T1W hyperintensity at the time of presentation with a new vertebral collapse, is a very useful diagnostic clue. Imaging with isotope bone scans or, where available, whole-body MRI is useful as it allows the identification of further foci of disease, particularly since these may not be symptomatic on initial presentation. Whole-body MRI also aids follow-up and response to treatment [47, 48, 52]. The combination of clinical and imaging features usually allows a confident diagnosis without the requirement for needle biopsy.
Conclusion reduces as the lesion heals. Soft-tissue extension may also be seen on MRI [43, 44]. CT-guided biopsy is frequently used to aid diagnosis. Tc99m bone scans are helpful to identify multilevel disease, but cannot reliably differentiate active from healing lesions, as both will show increased activity. Therefore, in the setting of multilevel disease, MRI can aid in deciding which vertebra to biopsy based on the presence of marrow oedema at an active level [8, 45]. Chronic recurrent multifocal osteomyelitis Chronic recurrent multifocal osteomyelitis (CRMO) is a condition of undetermined aetiology characterised by areas of sterile (non-bacterial) osteomyelitis [46] Spinal CRMO is rare, representing approximately 3 % of lesions [16, 47]. Despite this, the spine is the most common site of pathological fracture, usually affecting the thoracic region [16, 47, 48]. Lesions may range from lytic to sclerotic and mixed lesions are not uncommon. Radiographs may show a lytic lesion with a sclerotic border (Fig. 14a) or a completely sclerotic lesion, possibly indicating an advanced stage of the disease process (Fig. 14b). The sclerotic nature of a lesion will be optimally demonstrated on CT (Fig. 14c) and may be
Acquired vertebral collapse in the paediatric population represents a short differential of conditions, which may appear very similar on imaging, but have individual features that can aid differentiation, as described above. However, in many cases, biopsy may be required to confirm the diagnosis. In all cases, referral for expert review in a specialist Paediatric Oncology Centre is recommended. Conflict of interest No conflict of interest.
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435 27. Ilaslan H, Sundaram M, et al. Primary vertebral osteosarcoma: imaging findings. Radiology. 2004;230:697–702. 28. Meehan PL, Viroslav S, Schmitt Jr EW. Vertebral collapse in childhood leukemia. J Pediatr Orthop. 1995;15(5):592–5. 29. Carrière B, Cummins-Mcmanus B. Vertebral fractures as initial signs for acute lymphoblastic leukemia. Pediatr Emerg Care. 2001;17:258– 61. 30. Pandya NA, Meller ST, MacVicar D, Atra A, Pinkerton CR. Vertebral compression fractures in acute lymphoblastic leukaemia and remodelling after treatment. Arch Dis Child. 2001;85:492–3. 31. El Saleeby CM, Grottkau BE, Friedmann AM, Westra SJ, Sohani AR. Case records of the Massachusetts general hospital. Case 42011. A 4-year-old boy with back pain and hypercalcemia. N Engl J Med. 2010;364:552–62. 32. Parker BR, Castellino RA. Skeletal involvement in non-hodgkins lymphoma in paediatric oncologic radiology. St Louis: Mosby; 1977. p. 200–2. 33. Parker BR, Castellino RA. Skeletal involvement in hodgkins disease in paediatric oncologic radiology. St Louis: Mosby; 1977. p. 177–8. 34. Edeiken-Monroe B, Edeiken J, Kim EE. Radiologic concepts of lymphoma of bone. Radiol Clin North Am. 1990;28:841–64. 35. Hicks DG, Gokan T, O’Keefe RJ, et al. Primary lymphoma of bone: correlation of magnetic resonance imaging features with cytokine production by tumor cells. Cancer. 1995;75:973–80. 36. Stiglbauer R, Augustin I, Kramer J, Schurawitzki H, Imhof H, Radaszkiewicz T. MRI in the diagnosis of primary lymphoma of bone: correlation with histopathology. J Comput Assist Tomogr. 1992;16:248–53. 37. Traill Z, Richards MA, Moore NR. Magnetic resonance imaging of metastatic bone disease. Clin Orthop Relat Res. 1995;312:76–88. 38. Mukherjee D, Chaichana KL, Gokaslan ZL, Aaronson O, Cheng JS, McGirt MJ. Survival of patients with malignant primary osseous spinal neoplasms: results from the surveillance, epidemiology, and end results (SEER) database from 1973 to 2003. J Neurosurg Spine. 2011;14:143–50. 39. Sinha AK, Seki JT, Moreau G, Ventureyra E, Letts RM. The management of spinal metastasis in children. Can J Surg. 1997;40:218– 26. 40. Chlebna-Sokół D, Loba-Jakubowska E, Sikora A. Clinical evaluation of patients with idiopathic juvenile osteoporosis. J Pediatr Orthop B. 2001;10:259–63. 41. Dimar JR, Campbell M, Glassman SD, Puno RM, Johnson JR. Idiopathic juvenile osteoporosis. An unusual cause of back pain in an adolescent. Am J Orthop (Belle Mead NJ). 1995;24:865–9. 42. Sartoris DJ, Parker BR. Histiocytosis X: rate and pattern of resolution of osseous lesions. Radiology. 1984;152:679–84. 43. Bavbek M, Atalay B, Altinors N, et al. Spontaneous resolution of lumbar vertebral eosinophilic granuloma. Acta Neurochir (Wien). 2004;146:165–7. 44. Kaplan GR, Saifuddin A, Pringle JA, Noordeen MH, Mehta MH. Langerhans’ cell histiocytosis of the spine: use of MRI in guiding biopsy. Skeletal Radiol. 1998;27:673–6. 45. Gikas PD, Islam L, Aston W, et al. Nonbacterial osteitis: a clinical, histopathological, and imaging study with a proposal for protocolbased management of patients with this diagnosis. J Orthop Sci. 2009;14:505–16. 46. Jurriaans E, Singh NP, Finlay K, Friedman L. Imaging of chronic recurrent multifocal osteomyelitis. Radiol Clin North Am. 2001;39: 305–27. 47. Langendoerfer M, von Kalle T, Maier J, Dannecker GE. Spinal involvement in chronic recurrent multifocal osteomyelitis (CRMO) in childhood and effect of pamidronate. Eur J Pediatr. 2010;169: 1105–11. 48. Yu L, Kasser J, O’Rourke E, Kozakewich H. Chronic recurrent multifocal osteomyelitis: association with vertebra plana. J Bone Joint Surg Am. 1989;71:305–6.
436 49. Jansson A, Renner ED, Ramser J, Mayer A, Haban M, Meindl A, et al. Classification of non-bacterial osteitis: retrospective study of clinical, immunological and genetic aspects in 89 patients. Rheumatology (Oxford). 2007;46:154–60. 50. Khanna G, Sato T, Ferguson P, et al. Imaging of chronic recurrent multifocal osteomyelitis1. Radiographics. 2009;29:1159–77.
Skeletal Radiol (2014) 43:423–436 51. Fritz J, Tzaribatchev N, et al. Chronic recurrent multifocal osteomyelitis: comparison of whole-body MR imaging with radiography and correlation with clinical and laboratory Data1. Radiology. 2009;252:842–51. 52. Haydar AA, Gikas P, Saifuddin A. Case report: chronic recurrent multifocal osteomyelitis: a case report and role of whole-body MRI. Clin Radiol. 2009;64:641–4.
REVIEW ARTICLE
Paediatric acquired pathological vertebral collapse Hassan Hirji & Asif Saifuddin
Received: 24 July 2013 / Revised: 28 October 2013 / Accepted: 26 November 2013 / Published online: 9 January 2014 # ISS 2014
Abstract Vertebral collapse is a significant event in the paediatric patient with a real potential for associated deformity and morbidity. While in adults the causes tend towards the malignant, particularly metastatic and metabolic disease, the paediatric population demonstrates a different range of diagnoses. This article reviews the typical imaging findings of the more common underlying acquired pathological causes of vertebral collapse in children, including Langerhans cell histiocytosis, chronic recurrent multifocal osteomyelitis, osteogenesis imperfecta. Other causes include pyogenic osteomyelitis and tuberculosis and neoplastic lesions, either primary, metastatic or of haematological origin. Keywords Spinal diseases . Spinal neoplasms . Paediatric acquired pathological vertebral collapse
Introduction Vertebral collapse is an extremely rare, but significant event in the paediatric patient, with a real potential for associated pain, deformity and morbidity. While in adults the causes tend towards the malignant, particularly metastatic and metabolic disease, in the paediatric population a different range of differential diagnoses is encountered, reflecting the nature of the
A. Saifuddin (*) Royal National Orthopaedic Hospital, Stanmore, UK e-mail: [email protected] H. Hirji North West London Hospitals NHS Trust Northwick Park Hospital, Harrow, UK
developing spine with a higher preponderance of primary lesions. Furthermore, the natural on-going growth of the paediatric spine may permit good recovery even with conservative management. This article seeks to provide a review of the typical imaging findings of the more common underlying acquired pathological causes of vertebral collapse in children. Collapse secondary to trauma has not been included, nor have diseases of a congenital origin.
Anatomy and normal imaging appearances As in the adult, the spine consists of bony vertebrae separated by compressible intervertebral discs. The vertebrae have large bodies that consist of a dense outer bony cortex and contain the highly vascular marrow. Unlike the adult spine, the soft tissues are more flexible and the age-related changes of osteopenia and disc degeneration are less frequent, if at all present. The vertebral end plates are not fused, giving the spine the possibility of remodelling with restoration of almost normal height, even following quite severe and deforming disease. The arterial supply to the vertebral body is through periosteal branches, which penetrate the vertebral body at several sites adjacent to each endplate, and the lumbar artery. In addition, there are posterior arterial branches that pass across the posterior border of the vertebral body and anastomose near the midline [1, 2]. These are important to recognise as inflammatory and vasculitic processes will be predisposed to arise near the arterial vessels, increasing the destructive effects at these sites. The venous drainage is through small tributary vessels that pass through the medulla to a central venous channel, the basivertebral vein, which drains from the dorsal aspect of the vertebral body. Here it merges with a large valveless
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venous plexus, which allows the ready passage of infection and metastatic seeding, particularly from the pelvis or perineum [1, 3]. At birth, the marrow space is filled with red (haematopoietic) marrow. Over the first 5 years, this undergoes gradual conversion to yellow marrow. On MRI, red marrow has T1W signal intensity (SI) greater than muscle, but less than fat. As the child moves towards maturity, the red marrow is replaced by fatty, yellow marrow. This has a shorter T1 relaxation time giving a higher T1W signal and a lower T2W signal. A more detailed description of marrow signal in
Fig. 1 Pyogenic osteomyelitis in a 14-year-old girl. a Lateral radiograph of the thoraco-lumbar spine showing erosion of the anterior–superior corner of the L1 vertebra (arrow). b Sagittal T1-weighted spin echo (T1W SE) and c T2-weighted fast spin echo (T2W FSE) MR images showing end-plate erosion, loss of disc height and extensive marrow oedema-like signal intensity (SI; arrows) with minor anterior sub-ligamentous spread of infection. d Sagittal post-contrast fat-suppressed T1W SE MR image showing enhancement of the anterior soft tissue extension (arrow) and also focal disc enhancement. e Sagittal CT multiplanar reconstruction (MPR) showing end-plate erosions and medullary sclerosis (arrows) consistent with the relatively chronic nature of the disease process. f Sagittal short T1 inversion recovery (STIR) MR image shows normalisation of the marrow SI within T12 and L1, indicating healing with complete loss of the intervening disc
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children and its changes with maturation has been provided by Foster et al [4].
Imaging technique As with the adult spine, AP and lateral radiographs should first be obtained, with standing radiographs, if possible, depending upon the level of pain, allowing an assessment of overall spinal alignment. Following radiography, MRI will invariably be the next investigation, and the majority of cases can be
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Fig. 2 Pyogenic L2–L3 discitis in a 13-year-old boy. a Sagittal T1W SE, b sagittal STIR and c)axial T2W FSE MR images showing destruction of the disc, mild end-plate oedema and prominent posterior extension of the phlegmon deep to the posterior longitudinal ligament (PLL; arrows)
adequately diagnosed purely on this combination of imaging. In the setting of vertebral collapse, CT and scintigraphy add little further diagnostic information. The MRI technique for assessing the paediatric spine does not differ from the adult spine, typically comprising a combination of sagittal and axial T1W spin echo (SE) and T2W FSE sequences. The addition of a fat-suppressed sequence (STIR or fat-suppressed T2W FSE) is of value in the assessment of suspected neoplastic, infective or inflammatory disorders and imaging of the whole spine should always be performed to look for multilevel non-contiguous disease, both for the Fig. 3 Tuberculosis (TB) osteomyelitis of T3 in a 10-yearold girl. a Lateral plain radiograph of the thoracic spine shows marked anterior collapse and wedging of T3 (arrow) with focal kyphosis. b Sagittal T1W SE MR image shows associated anterior and posterior sub-ligamentous spread of infection with mild spinal cord compression (arrows)
purpose of overall disease staging, but also to aid in differential diagnosis. As in the adult spine, the administration of IV gadolinium is of particular value in suspected spinal osteomyelitis/discitis to aid in the differentiation of phlegmon from abscess. Depending upon the age of the child and/or the level of pain, general anaesthesia may be required. Diffusionweighted imaging may be misleading since increased marrow SI may be seen in 48 % of normal children [5]. If required, staging of the remainder of the skeleton can be achieved with whole-body bone scintigraphy, or for some conditions, such as suspected Langerhans’ cell histiocytosis
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(LCH), with radiographic skeletal survey. However, wholebody MRI using a combination of coronal T1W SE and STIR sequences is now becoming commonplace [6–8] When a diagnosis cannot be achieved based on clinical and imaging features alone, then consideration will have to be given to percutaneous needle biopsy, which is safely performed with CT guidance under general anaesthesia [9]
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the outer cortex and the integrity of the trabecular bone and marrow within. Diseases causing destruction of either of these components may lead to a loss of vertebral height. Vertebra plana occurs when the vertebral body is reduced to a single dense sclerotic band, often with preservation of the discs on either side.
Differentiating from trauma Acquired paediatric vertebral collapse Vertebral collapse occurs secondary to a failure in the mechanical integrity of the anterior and/or middle columns of the vertebral body. The vertebral body derives its strength from Fig. 4 TB osteomyelitis of the lumbo-sacral junction in a 16-year-old boy. a Sagittal T1W SE and b T2W FSE MR images showing diffuse marrow oedema-like SI in the L5, S1, S2 and S3 vertebrae. Note the absence of disc involvement and the extensive anterior subligamentous extension (arrows). c Coronal T2W FSE MR image showing a large left psoas abscess (arrows). d Axial T2W FSE MR image showing extension into the neural arch (arrows) as well as the large anterior sub-ligamentous collection
It can be difficult to differentiate between a pathological fracture and a post-traumatic injury, but this can be of vital importance in determining further care and future prognosis. Traumatic injuries have a preponderance in the cervical spine of young children and for the thoracolumbar spine in older
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children and teenagers [10]. The differentiation between a vertebral fracture due to trauma and one caused by pathological collapse will clearly depend upon the history of a significant injury, as well as the imaging features. Simple vertebral fractures with no underlying cause will have the same imaging features as wedge and burst fractures in adults. Features suggestive of simple trauma include marrow oedema involving mainly the upper aspect of the vertebral body with some residual fatty marrow, relative sparing of the pedicles, retropulsion of the posterior superior cortex and the absence of a surrounding soft tissue mass. The relative prevalence of the different causes of acquired paediatric vertebral collapse is difficult to determine, since it will be highly dependent upon the specialist nature of the treating centre. Our experience is in the setting of a tertiary referral spinal orthopaedic setting, in which case chronic recurrent multifocal osteomyelitis (CRMO) is anecdotally the commonest cause.
Infective causes
Fig. 5 Ewing sarcoma of C4 in a 15-year-old boy. Lateral radiograph showing lytic collapse of C4 with mild focal kyphosis (arrow)
Pyogenic osteomyelitis Pyogenic osteomyelitis is an uncommon presentation of bone infection, which may be due to almost any infectious pathogen. The most common agent is Staphylococcus sp., but other common organisms include H. influenza, Salmonella sp., E. coli and Neisseria gonorrhoeae. The infection classically reaches the spine via haematogenous spread within the venous plexus, although direct inoculation, such as accidental exposure during surgery is also seen. Sites of infection are classically in the lumbar spine, with the cervical and thoracic vertebrae less commonly affected. Unlike adults, in which the vertebral end plate is closed, the end plate allows the passage of infection through to the adjacent disc space. As such, infection may be seen to pass from an affected vertebral body to a contiguous vertebral body. Plain radiographs may show a reduction in vertebral body height. The preponderance is for anterior vertebral body involvement (Fig. 1a). MRI shows variable fluid within the disc space, which may show loss of height, erosion of the endplates and extensive marrow oedema-like SI within the adjacent vertebral bodies (Fig. 1b, c). Disc and vertebral enhancement will be seen following contrast agent administration (Fig. 1d). Depending upon the chronicity of the lesion, there may also be associated sub-chondral marrow sclerosis, best appreciated with CT (Fig. 1e). With adequate antibiotic therapy, marrow SI will return to normal (Fig. 1f). Other characteristic features of pyogenic discitis include epidural extension deep to the posterior longitudinal ligament (PLL; Fig. 2).
Tuberculous osteomyelitis Tuberculous infection of the spine (Pott’s disease) is an uncommon manifestation of tuberculosis (TB), but where the skeleton is affected, roughly half will have spinal disease [11]. It is most commonly seen in children in endemic areas. Classically occurring through haematogenous spread, the origin is frequently unknown, but approximately 50 % of children will have co-existing pulmonary involvement.
Fig. 6 Aneurysmal bone cyst (ABC) in a young boy. Antero-posterior (AP) radiograph of the lumbar spine showing collapse of the left side of the L3 vertebral body (arrows) with absence of the left pedicle
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characteristic feature of tuberculosis (Fig. 4d) [12, 13]. TB may also produce vertebra plana [9]. Diffusionweighted imaging has been found to have poor specificity (66 %) at distinguishing between tuberculosis and pyogenic osteomyelitis [14]
Infection typically affects the anterior vertebral endplate with granulomatous disease predominating in the early phase. Expansion of the lesion destroys the trabeculae and may lead to anterior collapse and subsequent wedging. Infective foci can erode through the cortex to form sub-ligamentous and soft-tissue abscesses. Kyphosis due to anterior wedging is a common feature (Fig. 3) [11]. The thoracic spine is the most common site of disease, followed by the lumbar and cervical spine. The disease is normally contiguous, but can occur at multiple noncontiguous levels, necessitating routine MR imaging of the whole spine [8, 9]. Tuberculous lesions show low SI on T1W imaging (Fig. 4a) and appear hyperintense on T2W (Fig. 4b) and STIR sequences. Unlike other forms of discitis, disc space narrowing is uncommon and preservation aids diagnosis (Fig. 4a, b). Involved discs may show increased signal on T2W sequences, which can be difficult to identify in the paediatric spine where the discs have a naturally high signal. Differentiating between tuberculous and pyogenic infections is aided by peripheral enhancement with gadolinium in TB, as opposed to more diffuse enhancement in pyogenic infection. Other classical features include large anterior sub-ligamentous and psoas abscesses (Fig. 4c, d). Furthermore, infection involving the posterior elements is a
Ewing sarcoma is the second most common malignant primary spinal tumour in children, peaking at the age of 15 years and commonly presenting with a combination of pain and neurological deficit. The tumour typically arises unilaterally in the neural arch with secondary involvement of the vertebral body [16]. A large extra-osseous mass is usually seen at the time of presentation, which may impinge on the canal causing neurological symptoms. Imaging features are of an expansile
Fig. 7 ABC of L2 in a 17-year-old girl. a AP radiograph shows lytic collapse of the left side of the L2 vertebral body with absence of the left pedicle (arrow) and a right thoraco-lumbar scoliosis. b Axial CT image showing the extensive vertebral destruction and the thinned expanded residual vertebral and neural arch cortex (arrows). c Corresponding axial
T1W SE MR image shows a lesion with heterogeneous internal SI characteristics (arrows). d Axial T2W FSE MR image demonstrates a low SI rim (arrows) and multiple fluid–fluid levels (arrowheads). e Axial post-contrast T1W SE MR image shows subtle septal enhancement throughout the lesion
Neoplastic causes Primary vertebral tumours are rare in children, with only one study demonstrating 8 affected children out of 1,971 cases of musculoskeletal tumours [15]. Nevertheless, it is important to recognise this group, as management is dependent on appropriate diagnosis and referral. Ewing sarcoma
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lesion with cortical thickening and destruction, which is predominantly lytic, with a minority showing a mixed appearance. In rare cases the tumour may arise within the vertebral body itself (Fig. 5). Tumour extension into the spinal canal is common with up to 91 % affected in some series [16, 17]. Metastases are to the lungs, bones and regional lymph nodes, often at the time of diagnosis [18]. Aneurysmal bone cyst Aneurysmal bone cysts (ABC) of the spine are benign, slowly growing, highly vascular lesions that predominantly affect the posterior elements unilaterally, but commonly extend into the vertebral body, where they may cause partial collapse or even vertebra plana [19]. ABCs may be primary in origin or secondary to other lesions such as osteoblastoma, giant cell tumour, chondroblastoma or fibrous dysplasia. They are twice as common in female subjects and usually present in the second decade of life. They are the second most common vertebral neoplasm [19]. Radiographs classically demonstrate a lytic lesion producing asymmetrical vertebral collapse
Fig. 8 Polyostotic fibrous dysplasia of the spine in a 13 year-old girl. a AP radiograph of the thoraco-lumbar junction, which shows collapse of the mildly sclerotic T11 vertebral body. Note also the involvement of the adjacent left 11th rib (arrows). b Axial and c sagittal CT MPR showing medullary sclerosis due to the ground glass matrix (arrows). A further lesion is seen in the inferior aspect of L1, which shows the classical thick sclerotic margin (short arrow), the “rind sign”
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owing to extension of the lesion from the neural arch into one side of the vertebral body, the absence of the ipsilateral pedicle being a classical feature (Fig. 6). The degree of collapse may be enough to produce a structural scoliosis (Fig. 7a). CT may show an “egg-shell” appearance of thinned expanded vertebral cortex (Fig. 7b). MRI demonstrates a characteristic, multi-loculated lesion with heterogeneous internal SI on T1W (Fig. 7c). A surrounding low SI rim may be evident on T2W sequences (Fig. 7d), which also classically demonstrate multiple fluid–fluid levels (Fig. 7d), representing sedimentation of blood products from recurrent haemorrhage within the cysts. Enhancing septae may be seen separating the fluid-filled cavities (Fig. 7e) [19]. Neurological compromise and cord compression have been associated with these lesions [20]. Fibrous dysplasia Fibrous dysplasia of the spine may be monostotic or polyostotic and can be seen as part of syndromes such as
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McCune–Albright. It most commonly affects the thoracolumbar region [21]. Spinal deformity is typically associated with the polyostotic form, which will also affect other parts of the skeleton [22]. In particular, involvement of the adjacent rib is a relatively common feature, which should suggest the diagnosis (Fig. 8a). The monostotic form is extremely rare and not commonly associated with collapse [21, 23]. Plain radiographs demonstrate a ground glass appearance, which may involve both the vertebral body and the posterior elements, and is optimally demonstrated on CT (Fig. 8b, c). Focal lesions may have a thick sclerotic margin, the “rindsign” (Fig. 8c). MRI shows reduced SI on both T1- and T2weighted sequences representing the fibrous component, or areas of fluid SI when there is associated cystic degeneration. Technetium 99 m MDP bone scan will normally demonstrate increased uptake in the affected regions of the bone [21, 23–25]. Osteosarcoma Osteosarcoma may develop as a primary lesion or secondary to spinal irradiation. Primary osteosarcoma is the most
Fig. 9 Osteosarcoma of T12 in a 16-year-old boy. a Coronal CT MPR shows lytic destruction and collapse of the right side of the vertebral body with a small paravertebral soft tissue mass (arrows). b Sagittal T2W FSE and c axial T1W SE MR images demonstrate diffuse vertebral marrow infiltration, pathological collapse and extra-osseous extension causing compression of the conus
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common primary malignant tumour of the spine in adults (excluding myeloma) and the eighth in children, with cases reported in children aged as young as 8 years [26]. The lesion typically involves the posterior elements, extending secondarily into the posterior vertebral body causing collapse, although less typically the lesion may be confined to the posterior body alone. Radiography and CT will frequently demonstrate mineralised matrix secondary to the deposition of osteoid. This may be extensive, producing an “ivory vertebra” appearance. In approximately 20 % of cases, the process may appear purely lytic (Fig. 9a). Extension into the vertebral canal is a common feature (Fig. 9b, c) [27]. Acute lymphoblastic leukaemia/lymphoma Acute lymphoblastic leukaemia/lymphoma (ALL) is a very rare cause of spinal collapse. Analysis by Meehan et al. found only 16 cases among 615 patients with leukaemia [28, 29]. This is most commonly seen in children under 5 years old, although cases are seen up to the second decade. Features of ALL include osteopenia, which can result in vertebral collapse in the absence of malignant marrow infiltration, and therefore
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Fig. 10 B-cell lymphoma in a 14-year-old boy. a Lateral radiograph of the lumbar spine showing diffuse osteopenia and mild collapse of T12 (arrow). b Sagittal T1W SE MR image of the cervico-thoracic spine showing mildly hyperintense intervertebral discs indicative of diffuse vertebral marrow infiltration and multilevel vertebral collapse (arrows). c Coronal STIR MR image of the sacrum showing diffuse marrow hyperintensity
Fig. 11 Osteosarcoma metastasis of L3 in a 17-year-old boy. a Lateral radiograph showing diffuse osteopenia mild anterior wedging of the L3 vertebra (arrow). b Sagittal T1W SE and c axial T2W FSE MR images demonstrate a hypointense metastasis in the anterior half of the vertebral body (arrows)
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no evident SI change in the vertebral bodies on MRI, while marrow involvement results in diffuse, homogenously low T1W and increased STIR SI 30–32]. There may be restoration of normal vertebral height through bone remodelling following treatment [32]. Similar appearances will be seen in childhood lymphoma (Fig. 10). Paediatric lymphoma may be primary or secondary. Primary lymphoma accounts for approximately 2–6 % of primary bone tumours in children, but more typically involves the long bones. Secondary lymphoma is more commonly nonHodgkins than Hodgkins (20 % vs 1–5 %) [33, 34]. Lymphoma may produce sclerotic or lytic lesions that may involve the whole vertebra and may have low T1W SI on MRI with a variable appearance on T2W [35–37]. Metastases Metastatic disease is less common in the paediatric population than in adults and has a different range of primary lesions, the most common being Ewing sarcoma and neuroblastoma, osteosarcoma, rhabdomyosarcoma, Hodgkin's disease, soft tissue sarcoma and germ cell tumour. [38] Vertebral metastases in children may derive from primary bone or soft tissue tumours. Secondary deposits from primary spinal bone tumours are also well recognised with Ewing sarcoma among the most common. These are associated with a poorer prognosis [39]. Metastases from extraosseous primaries include neuroblastoma and astrocytoma. Metastases are typically of low signal on T1W sequences replacing normal marrow and can be variable on T2 and STIR sequences [40] (Fig. 11). Whole-body MRI has been
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shown to have greater sensitivity than conventional imaging for bony metastases [7].
Miscellaneous causes Metabolic cause: idiopathic osteoporosis Idiopathic osteoporosis is a rare condition that most commonly presents in pre-pubescent children. It is characterised by bone demineralisation, but patients can be biochemically normal. Clinical features include pain in the spine and limbs, gait disturbance and muscle weakness. Radiographs demonstrate osteopaenia and may show vertebral collapse at multiple levels (Fig. 12). Metaphyseal compression in long bones has also been described and DEXA imaging will typically show
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Fig. 12 Idiopathic osteoporosis in a 16-year-old boy. a Lateral radiograph of the lumbar spine showing generalised osteopaenia and severe multilevel vertebral collapse (arrows). b Sagittal T2W FSE MR image demonstrates multilevel vertebral collapse with biconcave end-plates and secondary expansion of the intervertebral discs
Fig. 13 Langerhans cell histiocytosis (LCH). A 14-year-old boy with biopsy-proven LCH of C7. a Lateral cervical spine radiograph showing irregular, lytic vertebral collapse with anterior wedging and focal kyphosis. b Follow-up lateral radiograph shows progression to the vertebra plana. c Sagittal T1W SE and d T2W FSE MR images showing reduced T1W and increased T2W marrow SI. Note the maintenance of the cortical signal void of the C7 vertebral end-plates, the preservation of the adjacent discs and the extra-osseous extension (arrows)
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c
Fig. 14 Chronic recurrent multifocal osteomyelitis (CRMO). a Lateral radiograph of the thoracic spine in an 11-year-old girl showing collapse of the T8 vertebra (arrow). b Lateral radiograph of the thoracic spine in a 16year-old girl showing collapse of the T9 vertebra with marked loss of
vertebral height and diffuse medullary sclerosis (arrow). c Axial CT in the same patient as in b confirms the medullary sclerosis in the vertebral body with extension into both pedicles
reduced Z scores [41]. It is a disease of exclusion once other metabolic and genetic causes have been ruled out. Prevention of further vertebral fractures is the key to management, as the condition typically resolves spontaneously with time [42].
elements and may cause anterior wedging (Fig. 13a) [43]. It is one of the leading causes of pathological vertebral collapse in children, which may be so pronounced as to cause a vertebra plana (Fig. 13b). The disc spaces on either side of the collapsed vertebra are normally preserved, a feature seen clearly on MRI. Resolution of the disease can lead to restoration of vertebral body height [44]. Lesions are lytic and poorly defined on radiography and CT. MRI shows reduced marrow SI on T1W (Fig. 13c), increased SI on T2W (Fig. 13d) and STIR, and avid enhancement with gadolinium representing the hypervascular healing process. The T2/STIR hyperintensity
Langerhans cell histiocytosis Langerhans cell histiocytosis (LCH) produces eosinophilic granulomata within bone. These may be solitary or multiple, as in Hand–Schüller–Christian and Letterer–Siwe disease and may involve the spine. It is more common in male subjects and in particular in children under 5 years of age. The disease characteristically affects the vertebral bodies, often singly, but sometimes at multiple levels, typically sparing the posterior
a
a
b
b
Fig. 15 CRMO in a 16-year-old girl. a Sagittal T1W SE and b T2W FSE MR images showing severe collapse at the T9 level with marrow sclerosis (same case as in Fig. 2b and c), but also multilevel involvement manifest by the presence of oedema-like marrow SI (arrows). Note the absence of any soft-tissue extension
Fig. 16 CRMO in an 11-year-old girl. a Sagittal T1W SE and b T2W FSE MR images showing moderate collapse at the T8 level with mild reduction of marrow SI and bulging of the posterior vertebral body cortex (same case as in Fig. 2a), but also multilevel involvement manifest by the presence of end-plate collapse and fatty marrow SI (arrows) indicating healed lesions
434
Fig. 17 CRMO in an 11-year-old girl. Sagittal T2W FSE MR image showing multilevel mid-thoracic involvement with severe collapse of T6 resulting in marked focal kyphosis
Skeletal Radiol (2014) 43:423–436
confined to the vertebral body or may extend into the posterior elements. MRI shows altered marrow signal with reduced SI on T1W sequences (Fig. 15a). T2W hyperintensity is seen in acute disease (Fig. 15b). Typically, changes are confined to one or more vertebrae without crossing the adjacent discs or contiguous vertebrae, a feature that differentiates from bacterial osteomyelitis. Vertebral collapse may lead to vertebra plana, but unlike LCH, this does not recover following treatment [48–51]. The absence of extra-osseous extension also aids in differentiation from LCH. Healed lesions show a variable degree of collapse, but normal marrow SI, although the marrow may become hyperintense on T1W owing to the replacement of red marrow with yellow marrow (Fig. 16). Depending upon the degree of collapse, significant kyphosis can develop (Fig. 17) [51]. Multilevel disease is not uncommon, and the finding that healed lesions manifest by mild vertebral collapse and T1W hyperintensity at the time of presentation with a new vertebral collapse, is a very useful diagnostic clue. Imaging with isotope bone scans or, where available, whole-body MRI is useful as it allows the identification of further foci of disease, particularly since these may not be symptomatic on initial presentation. Whole-body MRI also aids follow-up and response to treatment [47, 48, 52]. The combination of clinical and imaging features usually allows a confident diagnosis without the requirement for needle biopsy.
Conclusion reduces as the lesion heals. Soft-tissue extension may also be seen on MRI [43, 44]. CT-guided biopsy is frequently used to aid diagnosis. Tc99m bone scans are helpful to identify multilevel disease, but cannot reliably differentiate active from healing lesions, as both will show increased activity. Therefore, in the setting of multilevel disease, MRI can aid in deciding which vertebra to biopsy based on the presence of marrow oedema at an active level [8, 45]. Chronic recurrent multifocal osteomyelitis Chronic recurrent multifocal osteomyelitis (CRMO) is a condition of undetermined aetiology characterised by areas of sterile (non-bacterial) osteomyelitis [46] Spinal CRMO is rare, representing approximately 3 % of lesions [16, 47]. Despite this, the spine is the most common site of pathological fracture, usually affecting the thoracic region [16, 47, 48]. Lesions may range from lytic to sclerotic and mixed lesions are not uncommon. Radiographs may show a lytic lesion with a sclerotic border (Fig. 14a) or a completely sclerotic lesion, possibly indicating an advanced stage of the disease process (Fig. 14b). The sclerotic nature of a lesion will be optimally demonstrated on CT (Fig. 14c) and may be
Acquired vertebral collapse in the paediatric population represents a short differential of conditions, which may appear very similar on imaging, but have individual features that can aid differentiation, as described above. However, in many cases, biopsy may be required to confirm the diagnosis. In all cases, referral for expert review in a specialist Paediatric Oncology Centre is recommended. Conflict of interest No conflict of interest.
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