Age / Sex : 45 / M

Chief complaint :

left thigh paresthesia


What is your diagnosis?

Two weeks later, you can see the final diagonosis with a brief discussion of this case (Please submit only one answer).



Courtesy : 정희석, Hee Seok Jeong/양산부산대학교병원, Pusan National University Yangsan Hospital

Cystic spinal schwannoma

Discussion

Findings:

about 2.1 x 1.8cm sized, well-defined high SI lesion on T2WI and iso SI lesion on T1WI with rim enhancement at left intradural extramedullary area of T12 level

Differential Diagnosis:

dermoid cyst, epidermoid cyst, arachnoid cyst, enterogenous cyst and cystic meningioma

Discussion:

Intradural extramedullary cystic schwannomas are rare.

Cystic schwannomas are most common in the lumbar region and occur rarely in the thoracic region.

MRI is the choice of modality for the evaluation of intradural spinal tumours. Schwannomas tend to have signal intensity equal to or less than that of the spinal cord on T1WI and mild to marked hyperintensity on T2WI. Schwannomas usually show fluid signal intensity on T2WI, which could be a useful predictor in its diagnosis.

Intradural extramedullary cysts, such as dermoid cysts, epidermoid cysts, arachnoid cysts, and enterogenous cysts, should also be differentiated from the severe cystic changes of spinal intradural extramedullary schwannomas. Dermoid cysts are diagnosed easily because of their fat content. Epidermoid cysts show various characteristics on MRI but they usually show signal intensity similar to that of CSF on T1- and T2-weighted sequences. They can have a thin or slightly thick peripheral capsule with or without enhancement. On diffusion weighted MRI, the epidermoid cyst shows restricted diffusion due to its keratin content in contrast to the severe cystic changes of spinal intradural extramedullary schwannomas . Presence of dermal sinus tract or other spinal dysraphism can be helpful in the diagnosis of both dermoid and epidermoid cysts. Intradural arachnoid cysts unusually arise from the region of the septum posticum at the thoracic level and have an extremely thin wall without enhancement. Enterogenous cysts are likely to develop anteriorly and be confined to the cervical region. Usually, their walls are very thin and not enhanced

References:

Surg Neurol Int. 2014 Aug 28;5(Suppl 7):S349-53.

J Coll Physicians Surg Pak. 2014 Feb;24(2):145-7

J Korean Soc Radiol 2015;72(6):393-400