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Atypical Spinal TuberculosisClinical History: 19-year-old boy with spinal tuberculosis. Findings: The imaging features on X-ray and CT scan were suggestive of metastatic disease of the spine. The atypical features of spinal tuberculosis which closely resemble metastatic disease are discussed here.Spinal tuberculosis presents in various locations and in different forms. Fortunately, regardless of the presentation, certain imaging features exist that favor tubercular infection over nontubercular pyogenic infections, neoplastic disease and other inflammatory diseases with similar clinical presentation. A 19-year-old boy complained of progressively worsening backache for 6 months. He complained of malaise and weight loss of 12 pounds over last 6 months. He had no neurological symptoms. On examination, he had minimalspinal tenderness at D9 level. General physical and systemic examination was normal. X-ray of spine showed permeative lytic destruction involving body and pedicles of D2, D9 and D12 vertebrae with paravertebral soft tissue density at D9 level. There was no evidence of loss of height of vertebrae. Disc spaces and vertebral end plates were normal. No lytic lesions in other bones were seen on skeletal survey. CT scan of spine showed para vertebral soft tissue masses noted on the right side of D2, left side of D9 and right side of D12 vertebral bodies. The soft tissue was seen to cause lytic destruction of the vertebral bodies and the pedicles at these levels with minimal extension into the spinal canal. However no significant spinal cord compression was noted. The adjacent discs are spared of destruction. On injection of non ionic contrast, the soft tissue masses were seen to show predominantly rim enhancement.The findings were suggestive of bone involvement by Non-Hodgkins’ lymphoma or metastatic disease in view of skip lesions of vertrebal bodies and pedicles, and sparing of intervertebral discs, although presence of paravertebral collection was a feature in favor of possible tubercular pathology. Incidentally, lung parenchyma revealed some infiltrative lesions in the right mid zone. HRCT sections through these lesions revealed ‘tree in bud’ appearance raising the suspicion of tuberculosis further.
Diagnosis: Atypical Spinal Tuberculosis Discussion: The spine is the most common site of skeletal tuberculous infection and the thoracolumbar region is the most commonly affected region.Tuberculosis of the spine affects the corners of the vertebral bodies, especially the anterior corner. This predilection may reflect tubercular seeding occurring via the paravertebral venous plexus of Batson rather than the more usual route of spinal arteries. Thereafter, tubercular infection spreads anteriorly or posteriorly into the vertebral body or disc. Three patterns of vertebral body involvement are recognized: paradiskal, anterior and central lesions.[1]
Paradiskal infection is adjacent to the disc space. The disc space narrowing is caused either by destruction of subchondral bone with subsequent herniation of the disk into the vertebral body or by direct involvement of the disk.[2] This is the most common pattern of spinaltuberculosis. Any tubercular vertebral lesion, such as anterior or central lesion, which does not have the aforementioned typical radiographic features, is referred to as atypical spinal tuberculosis. The importance of these lesions is that they are rare and difficult to differentiate clinically and radiographically from neoplastic process. Anterior lesions are subperisosteal lesions under the anterior longitudinal ligament. Pus spreads over multiple vertebral segments, stripping the periosteum and anterior longitudinal ligament from anterior surface of vertebral bodies. The periosteal stripping renders the vertebrae avascular producing anterior scalloping.[4] Central lesions are centered on the vertebral body with disc sparing. Vertebral collapse can occur, producing a vertebral plana appearance. The lesions may be in continuity, affecting from two to four contiguous vertebrae or may affect different levels in different region of spine. Posterior elements of vertebrae are rarely involved in isolation.[2] The differential diagnosis of tubercular spine includes pyogenic and fungal infections, sarcoidosis, metastasis, and lymphoma. In spinallesions, involvement of intervertebral discs, presence of paravertebral abscesses/collection and involvement of two contiguous vertebral bodies are suggestive of tuberculosis of spine. In neoplastic involvement of spine, disc spaces are usually spared and paravertebral abscesses are not seen although solid extraosseous soft tissue component may be associated if vertebral bodies are destroyed. Skip or non consecutive multifocal involvement of spine also favors neoplastic lesion. In central and posterior element forms of tuberculosis, only biopsy can provide diagnosis. Therefore, a high index of suspicion is required for spinal tuberculosis even in atypical presentations in areas with high endemicity of this infection.
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In Indian subcontinent Tuberculosis should be kept in mind if we see such cases. More over history taking is again important; we often miss several clues if history part is missed.