osteomas are rare , slow growing lesions composed of compact bone that occur almost exclusively in the skull [ 2 , 7 ] , most often in the inner and outer table of the calvarium or in the bones of the face or mandible [ 1 , 12 , 13 ] . the prevalence of this disease amounting those who have had sinus radiographs has been estimated to be 0.42% . although these lesions may cause sinusitis or exophthalmos when they arise from the wall of the nasal sinuses or the orbit , cranial osteomas often cause no symptoms and are discovered incidentally . primary intra - canal osteomas are extremely rare . to the authors knowledge , at the time of writing , only 14 cases of osteomas of the spine had been reported , in which only seven cases were in the english literature [ 46 , 8 , 9 , 11 ] . the purpose of this article is to report on two patients who presented with cervical intra - canal osteoma . a 56-year - old man had presented with paresis and weakness of his extremities after a hyperextension injury of the cervical spine in august 2002 . physical examination demonstrated limitation in neck rotation , and motor weakness of the extremities with strength 3/5 in upper extremities and 4/5 in lower extremities . the biceps tendon reflex , patellar tendon reflex , and achilles tendon reflex were hyperactive , and the hoffman and babinski reflex were positive bilaterally . sustained ankle clonus was present , bilaterally . b cervical lateral view x - ray showed high density at c23 level , the facet joints between c2\c3 were obscure . c ct scan through the intervertebral foramen between c2 and c3 showed the tumor occupied more than 60% canal and the vertebral shape changed , caused by the chronic pressure . d three dimensions ct reconstruction showed the three - dimension relationship between the tumor and the cervical spinal canal . e middle sagittal plane t1wi mri showed the spinal cord was pressed by the tumor . f the same plane as c after operation , showed the whole decompression of the spinal canal , part of the tumor , near the vertebral artery was left . g the same plane as e after operation , showed the whole decompression of the cord and spinal canal . h , i the pathological study showed that the lesion was composed of uniformly dense , compact , cortical - like mature lamellar bone . b cervical lateral view x - ray showed high density at c23 level , the facet joints between c2\c3 were obscure . c ct scan through the intervertebral foramen between c2 and c3 showed the tumor occupied more than 60% canal and the vertebral shape changed , caused by the chronic pressure . d three dimensions ct reconstruction showed the three - dimension relationship between the tumor and the cervical spinal canal . e middle sagittal plane t1wi mri showed the spinal cord was pressed by the tumor . f the same plane as c after operation , showed the whole decompression of the spinal canal , part of the tumor , near the vertebral artery was left . g the same plane as e after operation , showed the whole decompression of the cord and spinal canal . h , i the pathological study showed that the lesion was composed of uniformly dense , compact , cortical - like mature lamellar bone . h : 100 , i : 400 we performed a leminectomy of c2 and c3 . in the operation , we found that the tumor was adhesive with the left side vertebral artery . to avoid the injury of the artery , part of the tumor , near the vertebral artery , was left . the pathological study showed that the lesion was composed of uniformly dense , compact , cortical - like , mature lamellar bone ( fig . the patient s joa score increased from 11 to 16 ( table  1 ) . table  1joa score of the two cases before and after therapybefore therapyfollow - upcase 1case 2case 1case 2motor  upper extremity2133  lower extremity2243feeling  upper extremity1122  trunk2222  lower extremity2222sphincter2233total11101615 joa score of the two cases before and after therapy a 49-year - old man had experienced paresis and weakness of his extremities after a weight - hit injury of the head in november 2002 . physical examination showed moderate motor weakness and hypoesthesia of the upper extremity , with strength 3/5 in upper extremities and 4/5 in lower extremities . the biceps , patellar , and achilles tendon reflexes were hyperactive , and the hoffman and babinski reflexes were positive bilaterally . preoperative imaging study demonstrated lamina fracture of c3 , traumatic instability of c35 , and a cortical like solid lesion at the left side of c2 lamina . 2a cervical lateral view x - ray showed high density at c23 level , the facet joints between c2\c3 were obscure , traumatic instability of c35 . b ct scan through c2 showed the tumor at the left side of the lamina , occupied about 20% canal , and the left side lamina of the c2 became thicker . d three - dimension ct reconstructive image showed complete decompression a cervical lateral view x - ray showed high density at c23 level , the facet joints between c2\c3 were obscure , traumatic instability of c35 . b ct scan through c2 showed the tumor at the left side of the lamina , occupied about 20% canal , and the left side lamina of the c2 became thicker . d three - dimension ct reconstructive image showed complete decompression we performed a laminectomy of c3c4 and part of c2 , as well as internal fixation of c35 , using pedicle screw system . the pathological study showed that the lesion was also composed of uniformly dense , compact , cortical - like , mature lamellar bone without nidus ( not shown ) . lateral view x - ray after operation showed the reconstruction of the stability by the pedicle screw system and lamina decompression of c34 and part of c2 . three dimension ct reconstructive image showed complete decompression of the spinal cord ( fig . then , with hard cervical brace protection , the patient was permitted to ambulate , and he noted gradual improvement of strength in his upper extremity also . after 15  months , the muscle strength was 4/5 in upper extremity and 5/5 in lower extremity a 56-year - old man had presented with paresis and weakness of his extremities after a hyperextension injury of the cervical spine in august 2002 . physical examination demonstrated limitation in neck rotation , and motor weakness of the extremities with strength 3/5 in upper extremities and 4/5 in lower extremities . the biceps tendon reflex , patellar tendon reflex , and achilles tendon reflex were hyperactive , and the hoffman and babinski reflex were positive bilaterally . sustained ankle clonus was present , bilaterally . b cervical lateral view x - ray showed high density at c23 level , the facet joints between c2\c3 were obscure . c ct scan through the intervertebral foramen between c2 and c3 showed the tumor occupied more than 60% canal and the vertebral shape changed , caused by the chronic pressure . d three dimensions ct reconstruction showed the three - dimension relationship between the tumor and the cervical spinal canal . e middle sagittal plane t1wi mri showed the spinal cord was pressed by the tumor . f the same plane as c after operation , showed the whole decompression of the spinal canal , part of the tumor , near the vertebral artery was left . g the same plane as e after operation , showed the whole decompression of the cord and spinal canal . h , i the pathological study showed that the lesion was composed of uniformly dense , compact , cortical - like mature lamellar bone . b cervical lateral view x - ray showed high density at c23 level , the facet joints between c2\c3 were obscure . c ct scan through the intervertebral foramen between c2 and c3 showed the tumor occupied more than 60% canal and the vertebral shape changed , caused by the chronic pressure . d three dimensions ct reconstruction showed the three - dimension relationship between the tumor and the cervical spinal canal . e middle sagittal plane t1wi mri showed the spinal cord was pressed by the tumor . f the same plane as c after operation , showed the whole decompression of the spinal canal , part of the tumor , near the vertebral artery was left . g the same plane as e after operation , showed the whole decompression of the cord and spinal canal . h , i the pathological study showed that the lesion was composed of uniformly dense , compact , cortical - like mature lamellar bone . h : 100 , i : 400 we performed a leminectomy of c2 and c3 . in the operation , we found that the tumor was adhesive with the left side vertebral artery . to avoid the injury of the artery , part of the tumor , near the vertebral artery , was left . the pathological study showed that the lesion was composed of uniformly dense , compact , cortical - like , mature lamellar bone ( fig . the patient s joa score increased from 11 to 16 ( table  1 ) . table  1joa score of the two cases before and after therapybefore therapyfollow - upcase 1case 2case 1case 2motor  upper extremity2133  lower extremity2243feeling  upper extremity1122  trunk2222  lower extremity2222sphincter2233total11101615 joa score of the two cases before and after therapy a 49-year - old man had experienced paresis and weakness of his extremities after a weight - hit injury of the head in november 2002 . physical examination showed moderate motor weakness and hypoesthesia of the upper extremity , with strength 3/5 in upper extremities and 4/5 in lower extremities . the biceps , patellar , and achilles tendon reflexes were hyperactive , and the hoffman and babinski reflexes were positive bilaterally . preoperative imaging study demonstrated lamina fracture of c3 , traumatic instability of c35 , and a cortical like solid lesion at the left side of c2 lamina . 2a cervical lateral view x - ray showed high density at c23 level , the facet joints between c2\c3 were obscure , traumatic instability of c35 . b ct scan through c2 showed the tumor at the left side of the lamina , occupied about 20% canal , and the left side lamina of the c2 became thicker . d three - dimension ct reconstructive image showed complete decompression a cervical lateral view x - ray showed high density at c23 level , the facet joints between c2\c3 were obscure , traumatic instability of c35 . b ct scan through c2 showed the tumor at the left side of the lamina , occupied about 20% canal , and the left side lamina of the c2 became thicker . d three - dimension ct reconstructive image showed complete decompression we performed a laminectomy of c3c4 and part of c2 , as well as internal fixation of c35 , using pedicle screw system . the pathological study showed that the lesion was also composed of uniformly dense , compact , cortical - like , mature lamellar bone without nidus ( not shown ) . lateral view x - ray after operation showed the reconstruction of the stability by the pedicle screw system and lamina decompression of c34 and part of c2 . three dimension ct reconstructive image showed complete decompression of the spinal cord ( fig . then , with hard cervical brace protection , the patient was permitted to ambulate , and he noted gradual improvement of strength in his upper extremity also . after 15  months , the muscle strength was 4/5 in upper extremity and 5/5 in lower extremity congenital disease , rheumatoid arthritis , fracture and dislocation , and other systemic diseases can cause the compression of the upper cervical spinal cord . osteoma is defined by who as a benign lesion consisting of well differentiated mature bone tissue with a predominantly laminar structure , and showing very slow growth . osteomas are bosselated , round to oval sessile tumors that project from the subperiosteal or endosteal surfaces of the cortex . they are composed of a composite of woven and lamellar bone that is frequently deposited in a cortical pattern with haversian - like systems . some variants contain a component of trabecular bone in which the intertrabecular spaces are filled with hematopoietic marrow . only occasionally have these lesions been reported in extracranial locations ( table  2 ) . in 1980 , pecker et al . they used a lateral interscalenic approach to excise the lesion . in 1986 , lantsman reported six cases of osteoma in spine , but the article was in russian , no more details could be reviewed . in 1993   and 1996 , they performed an anterior prevascular extra oral approach . in 1996 , peyser reported 11 cases of extracranial osteoma , in which five were in spine , one in the cervical spine , two in the lumbar spine and two in the scrum spine . in 1998 , rengachary reported that another osteoma affected the cervical spine . table  2cases reported in the literaturereferencesarticle languagecase numbersite of the lesionrecurredrengachary english1cervicalnopeyser english5cervical ( 1 ) , lumbar ( 2 ) , sacrum ( 2)one pain recurredlaus english1cervicalnolaus italy1cervicalnolantsman russian6spinenopecker french1cervicalnototal14laus m. reported the same case in english and italy cases reported in the literature laus m. reported the same case in english and italy the diagnosis of intra - canal osteoma is still confusing . in peyser s series , none of the cases had correct diagnosis before the operation . in our cases , the rontgenographic study before operation could give some clues , but the final diagnosis still depended on the pathological findings . histologically , the reactive bone induced by infection and trauma may be similar with a true osteoma . however the differential diagnosis can be made by the tumor s site and pertinent history . traumatic reactive bones are most frequently observed in relation to the femur , beneath the quadriceps , in relation to the adductor magnus ( the so - called rider s bone ) or in relation to the medial collateral ligament of the knee joint . the condition is also not infrequent at the elbow , the exostosis forming in the intermuscular planes of the brachialis following dislocation . injury leads to the formation of a subperiosteal hemorrhage , the periosteum being detached by muscular traction . if the periosteum remains intact , the hematoma may become absorbed ; but if the periosteal reapposition and the absorption of the blood clot are prevented , traumatic bone overgrowth may occur . however , this condition could not occur at the endosteum . in the case of infective reactive bones , an infection history of relevant site cranial osteomas often cause no symptoms and are discovered incidentally , although these lesions may cause sinusitis or exophthalmus when they arise from the wall of the nasal sinuses or the orbit . it would be expected that the symptoms of spinal osteoma would depend on the location of the lesion and its relationship with the peripheral tissue . as rengachary   and laus [ 5 , 6 ] reported , the symptom of the spinal osteoma was caused from spinal cord or nerve root pressure . however in peyser s series all but one of the patients was symptomatic and had dull , aching pain at the time of the initial presentation . in our series , the two cases had no symptom before the injuries . it may be because osteomas are benign and very slow - growing lesions . and since the lesions cause spinal canal stenosis , they can cause the spinal cord to be more easily damaged by minor injury . the growth potential of osteoma remains unclear , as we know the cranial osteomas grow very slowly . peyser s excellent work showed us the growth potential feature of the spinal osteoma . in their series , one patient who had a juxtacortical osteoma of the cervical spine , showed no major change on serial ct scans performed twelve years apart . however , another patient s sacral osteoma showed significant growth on serial radiographs performed 18  years apart . the method of surgical management of an osteoma depends on the growth feature of the tumor . the aim of surgical management of spinal osteoma is decompression and stabilization if instability exists . peyser performed three total and two subtotal excisions , in the case series of osteomas , none recurred . however in one of the patients , partial resection of an osteoma from the body of the fifth lumbar vertebra resulted in no relief of pain and necessitated an additional procedure to remove the remainder of the lesion . in our series , it was relatively easy to perform an en bloc excision in the second case . in the first case , in view of a patient s age and risk of vertebral artery injuries , a subtotal excision was performed , also with satisfied short time outcome . however , the follow - up was not long enough to observe the recurrence . the incidence of intra - canal osteomas is rare . it can cause upper cervical myeolopathy . the rontgenographic study before operation can give some clues , but the final diagnosis still depends on the pathological findings . surgical treatment , either en bloc or subtotal excision of the lesion ,
osteoma is a common benign tumor . 
 it occurs dominantly at the skull bone . 
 outside skull osteoma is rare , and primary intra - canal osteoma is extremely rare . to the author s knowledge , 
 only 14 cases of osteomas of the spine had been reported , in which only seven cases were in english literature . 
 the authors reported two rare cases of intra - canal osteoma of the upper cervical spine with cord compression . included 
 are pertinent history , physical examination , rontgenographic evaluation before and after operation , surgical interventions , pathological study , and outcome . 
 the available literature is also reviewed . 
 on systemic examination and rontgenographic study , these two cases were found to have bone tumor in the upper cervical canal . 
 surgical interventions were performed , one with an en bloc excision , the other with a subtotal excision . 
 the pathological study demonstrated a diagnosis of osteoma . 
 after a follow - up with 20 and 15  months , the clinical symptoms of both cases significantly improved .