Cauda Equina Tumour-Differentials

29 yr old lady comes with gradually increasing pain and weakness of both lower limbs  including buttocks region. Routine MRI shows solitary, enhancing, well defined ,glomus shaped , nodule intramedullary region possibly  from filum  terminale internum with separation of nerve fibers of cauda at L3 level with no clumping of nerve roots or bony anomaly or disc disease  or conus  disease. Case by Dr MGK Murthy and Mr Hariom.

What is the diagnosis ?

It is of  intramedullary  neoplastic etiology and probably represents    ependymoma (commonest in this region, enhancement, and age group)

Differentials include extruded discs (not likely as no significant disc prolapse is identified otherwise and  the enhancement  ) spinal haemangioblastoma (no mural nodule), neurofibroma and schwannoma(not homogenous and intense in enhancement  as  well as no extension along the intervertebral foramina),Lipoma, dermoid and epidermoids (though relatively bright on T1, enhancement  goes against these),meningioma(though T2 low , enhancement is not typical and location is unusual), paraganglioma(intense enhancing nodule is the rule )and lastly the ever mimicker of neoplasm in our country tuberculoma (no other evidence of TB otherwise )

Teaching points:

-Spinal cord ends at lower border of L1 as conus in adults

-filum continues as strand of connective tissue for 15 cms appx with first 5-6 cms having central canal as well

-filum terminale internum continues as externum to coccyx after piercing the dura caudally