Age / Sex : 68 / F

Chief complaint : Both lower limb weakness (2 months ago)

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 : Sung Gyu Moon, Konkuk University Hospital

Discussion

Answer:  Tuberculous spondylitis

Findings:

Bone destructing mass mainly involving posterior column of T7 with large paravertebral and epidural mass formation, no involvement of intervertebral discs

• extending right 7^th rib head and partially posterior column of T8


• epidural mass causing thoracic spinal cord compression dorsally


• intermediate hyperintense on T2WI, isointense on T1WI and well-enhancement, having internally irregular non-enhancing necrotic portion

Differential Diagnosis:

metastatic neoplasm

pyogenic spondylitis

Discussion:

Basic pathology in tuberculous spondylitis is combination of osteomyelitis and arthritis involving more than one vertebra. In adults spinal TB classically present as spondylodiscitis involving the intervertebral disc secondarily from adjacent infected vertebra whereas in children the disease primarily starts from the intervertebral disc due to the vascularized nature.

Relative intervertebral disc preservation, vertebral endplates erosions, anterior wedging, pre & paravertebral and intraosseous abscesses with a subligamentous spread, vertebral body collapse, extradural, subdural and intramedullary tuberculomas are useful diagnostic clues for tuberculous spondylitis in MRI. On MRI, typical tuberculous spondylitis appears as the involved vertebra and adjacent disc shows decreased signal intensity on T1W and increased signal intensity on T2W images with reduction of disc height and soft tissue component or collection in the paravertebral and intraspinal compartment. Tubercular involvement of posterior element is relatively less frequent. Thin and smooth enhancement of abscess wall and well defined paraspinal abnormal signal is more in favor of tubercular abscess.

Contiguous involvement of two or more vertebral bodies are usually seen in spinal tuberculosis by hematogenous spread through the one vertebral artery feeding two adjacent vertebrae. Noncontiguous multiple level vertebral body involvement is rarely seen in tuberculous spondylitis and only two level involvements is seen in most of the studies. A study showed multiple level skip lesions were seen in 23.7% without involvement of intervertebral discs. Multilevel skip lesions of spine with sparing of intervertebral discs and absence of paravertebral soft tissue component favors neoplastic lesion whereas the presence of paravertebral lesion/collection favors tuberculous pathology.

Posterior element involvement is very rare in tuberculous spondylitis, however isolated posterior element involvement may be seen without other changes. A study reported that 10% of their tuberculous spondylitis cases having isolated posterior arch involvement. Other study showed 54.2% cases of atypical tuberculous spondylitis shows posterior elements involvement.

Differential diagnosis of multiple spinal lesions must include tuberculous spondylitis, metastatic neoplasm and pyogenic spondylitis. Nowadays presentation of tuberculous spondylitis are variable and atypical, hence whole body bone scan or MRI spine will be helpful in the diagnosis.

At times tubercular spondylitis may have a very bizarre appearance so that it cannot be differentiated from neoplastic lesions. Sometimes it presents without any bony involvement. It presents in a similar fashion to malignant deposits in the spine. In a single vertebra disease nutrition of the disc continues from the side of the healthy vertebra and hence the disc stays normal. Hence disc involvement is not always necessary in spinal tuberculosis.

Atypical tuberculous spondylitis can be best evaluated with MRI, and it includes spondylitis without discitis, isolated central lesion in single vertebral body, non-contiguous skip vertebral body lesions, isolated posterior vertebral elements involvement and isolated intraspinal canal lesions.

References:

Spinal Tuberculosis Resembling Neoplastic Lesions on MRI. J Clin Diagn Res. 2015 Nov;9(11):TC01-3

MRI assessment of the spine : infection or an imitation? Radiographics 2009; 29:599-612