Paraspinal mass - peripheral neuroectodermal tumor

Case contributed by Emtenan Meer


A previously healthy boy who presented with a progressive lower back pain for 3 weeks.

Patient Data

Age: 11 years
Gender: Male

Frontal x-ray shows an absent right L5 transverse process with shortening of the corresponding vertebral body.

The lateral x-ray shows a heterogeneous collapsed 5th lumbar vertebral body 


Enhanced axial CT images show an enhancing large para-spinal soft tissue mass at the level of the L5 vertebral body measuring about 5 x 5 x 4 cm which extends into the right sided neural foramina at L4-5 and L5-S1 with central canal extension at these levels causing thecal sac compression. There is lateral displacement of the right psoas muscle as well as anterior displacement to the common iliac vessels without evidence of invasion.

Coronal images in the bone window better demonstrate  the destruction of the L5 vertebral body, its right sided pedicle and transverse process. 

Case Discussion

The differential diagnosis for a paraspinal/perivertebral mass in a child is wide and includes benign and malignant etiology. Malignant lesions such as chondrosarcoma, Ewing sarcoma, peripheral neuroectodermal tumor (PNET) and neuroblastoma metastasis, amongst others. Benign lesions would not usually show bone destruction.

In this case, histopathology showed malignant small round cell tumor suggestive of Ewing sarcoma versus peripheral neuroectodermal tumor.

PNET is an uncommon and aggressive malignant tumor, accounting for 1% of sarcomas. The peak incidence is at adolescence. Retroperitoneal PNET  can occur in the pararenal space, perinephric space, presacral space and other locations. 

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Case information

rID: 69051
Published: 1st Jul 2019
Last edited: 26th Jul 2020
Inclusion in quiz mode: Included
Institution: King Abdulaziz University Hospital

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