OBJECTIVETo explore CT and MRI manifestations of the axial area peripheral primitive neuroectodermal tumors (pPNETs) in order to improve the knowledge of this disease.

METHODSThe clinical data of 10 patients with pPNETs underwent pathologically confirmed were retrospectively analyzed from October 2008 to May 2014. There were 7 males and 3 females, aged from 8 to 49 years old with median of 23.6 years. The preoperative multi-slice spiral CT scan was completed in 3 cases, plain CT scan and enhancement in 4 cases; MRI and enhancement scanning in 5 cases; and among them, 2 cases underwent both MRI and CT scan.

RESULTSIn-bone type was found 6 cases and out-bone type was found 4 cases. Three cases occurred in sacral vertebrae, 2 cases in lumbar vertebrae, 1 case in cervical vertebrae, 1 case in cervical spinal canal, 1 case in coccyx, 1 case in the right iliac bone, 1 case in presacral space. Cross sectional the smallest tumor maximum level was 1.1 cmx 1.2 cm in size, the biggest tumor was 8.0 cm x 9.2 cm, the median size was 4.4 cm x 5.7 cm, of them, the tumor of maximal diameter larger than 5 cm had 6 cases. Except 2 cases-without destruction of bone, the other 5 cases with osteolytic destruction, 2 cases with calcification, 1 case with mixed. Equidensite was main in CT scan, 1 case with uniform density, other 6 cases with uneven density,in which 3 cases with "floating ice" change; 1 case with moderate strengthening, other 3 cases with obviously strengthening, 2 cases with multiple small blood vessels in enhancement scanning. MRI of 5 cases showed the signal of isointensity on T1WI, the slightly high signal on T2WI and the signal was not uniform; after enhancement scan, the signal of 5 cases obviously enhanced. Two patients complicated with vertebral compression fractures, no periosteal reaction was found in all patients, and no the destruction of intervertebral disk was found in 5 patients of MRI scan.

CONCLUSIONThe axial area pPNETs is common among children and the youth, and the mass often is huge. The mass of in-bone type often envelopes the vertebral body, and main located on prevertebral space, all associated with bone destruction, osteolytic destruction is common, and primary vertebral bodies also is common, attachment primary or involvement is few found, it can involve the spinal canal and anterior wall of spinal canal is common, some cases complicate with multiple newly born small vessels. The mass of out-hone type in deep soft tissue is common, minority primary spinal canal, many complicated with vertebral bone destruction, osteolytic destruction was main. The intervertebral disk was not invaded and intervertebral space has not stenosis. CT scan offer complicate with "floating ice" sign, and in-bone type is common. Isointensity is main on MRI TlWI and slightly longer signal is main on MRI T2WI, strengthening signal is obvious.