Symptomatic Tuberculous Ligamentum Flavum Cyst Treated by Full Endoscopic Resection: Review with Technical Notes

BACKGROUND: Tuberculosis (TB) of the posterior spinal element is an uncommon condition. In a developed country its diagnosis is becoming difficult due to low incidence. CASE DESCRIPTION: A 60-year-old lady presented with low back pain and right leg pain for 6 months. On examination there was tenderness over L4 and L5, a positive straight leg raise test at 70 degrees on the right side and free on the left, and sensory involvement on the right L5 dermatome. Initial magnetic resonance imaging (MRI) showed an L4-5 ligamentum flavum cyst, high signal intensity in the right pedicle and facet joint. It was considered to be a degenerative spinal disorder. Later MRI showed increased size of the cyst, and computed tomography revealed erosion of the right pedicle of the L5 vertebrae, which raised the suspicion of the tubercular pathology. Initially the patient was managed for a degenerative spinal disorder. Later, when tubercular pathology was suspected, she underwent full endoscopic uniportal stenosis decompression and excision biopsy of the cyst. The histology of the cyst revealed chronic granulomatous inflammation with central necrosis. The diagnosis of a TB cyst was confirmed, and antitubercular therapy was started. CONCLUSION: TB of the posterior elements of the spine is a diagnostic challenge in developed parts of the world. We describe the first likely case of tubercular ligamentum flavum cyst, which was managed by a full endoscopic uniportal approach.