Background Osteoarticular tuberculosis represents 2 to 5% of all forms of tuberculosis. Spinal location is the most common and occurs in at least 50% of cases and concerns the thoracolumbar spine in 80% of cases. Isolated sacral tuberculosis is rare.

Objectives We report three cases of isolated sacral tuberculosis.

Methods The medical records of 3 patients diagnosed with isolated sacral tuberculosis were reviewed. Clinical, biological, and radiological evidence leading to the diagnosis of sacral tuberculosis were precised.

Results Case 1: Mrs. D.H. 30 years-old presented with right inflammatory lombo-sciatic pain that worsened 2 months before, with an undetermined weight loss. Clinical examination revealed stiffness of the lumbosacral spine without neurological deficit. Laboratory tests showed an ESR of 90 mm and CRP at 45 mg/l. The tuberculin skin test was positive at 15 mm. The search for Koch’s bacillus in sputum and urine was negative. The pelvis radiographs showed an osteolytic lesion of the sacrum extended to the right sacroiliac joint. Computed tomography confirmed the existence of an osteolytic lesion with a pelvic collection. MRI showed the presence of sacroiliitis with fluid collection interesting sacral and iliac bones, and adjacent soft gluteal tissues. Histological study of sacral biopsy found caseo-follicular tuberculosis. The patient was treated with antibacillary chemotherapy for a period of 9 months with good recovery.

Case 2: Mrs. A.H. aged 23, presented with left S1 lombosciatic pain lasting for 5 months and accompanied by fever, night sweats and weight loss of 20 kg. Clinical examination found lumbar stiffness with no signs of neurological deficit. The tuberculin skin test was positive at 18 mm. Search for Koch’s bacillus in sputum was negative. Radiographs of the pelvis were unremarkable. CT-Scan revealed pre-sacral and retro-acetabular abscessed collections with lysis of the vertebral body of S2. Pelvic MRI evidenced collections fusing to the sacral ala and left buttock. The patient underwent surgical drainage of the collections and sacred biopsy. Histological examination showed epithelioid granuloma with giant cells with caseous necrosis. An anti-bacillary chemotherapy was prescribed for a period of 9 months. The evolution after 4 months treatment was marked by the regression of low back pain and radicular pain.

Case 3 Mrs. A.M. aged 35, complained of right lombosciatic pain lasting for 1 year without neurological deficit on clinical examination. CT scan of the pelvis showed right sacral lytic lesion extended to the sacral canal. Histological examination revealed a caseous granuloma and multinucleated giant cells. The patient received anti-bacillary chemotherapy for a period of one year with a significant improvement.

Conclusions Isolated sacral tuberculosis is exceptional and its diagnosis is often delayed. Thus, it should always be suspected in any lytic process of the sacrum especially in endemic areas of tuberculosis, to prevent or at least reduce the morbidity of this disease that is generally curable.

Disclosure of Interest None Declared