Tuberculosis is a multisystem disease with numerous presentations and manifestations. It is the most common cause of infectious disease-related mortality worldwide. Extra-pulmonary TB incidence is 20.8%. Bone and joint involvement are the third most common, comprising 10-15% of cases. Tuberculous spondylitis is the most common manifestation of bone & joint involvement, accounting for approximately 40-50% of these cases.

Sacroiliac joint (SIJ) involvement has been reported in up to 9.7 percent of patients with bone & joint skeletal tuberculosis. Lack of awareness of this uncommon infection often leads to diagnostic delay and increased morbidity. Here we are presenting a rare case of SIJ skeletal tuberculosis. A 46 yrs. male presented with a history of intermittent fever, anorexia, malaise and a pus discharging wound (sinus) on the left Lower abdomen since 1 & ½ years.

On examination he was found to be febrile and he had continuous discharging sinus of 3 cm. In left iliac region. His spine and neurology examination was found to be normal. His abdomen examination revealed a diffuse tenderness in Left lower region. Provisional diagnosis of psoas abscess (cold abscess) with draining sinus was considered.

His CBC was normal, CRP was elevated 78mg/L and ESR 53mm at 1hr. His Xray & MRI of spine was found to be normal.

Surgical drainage & biopsy of the Sacroiliac joint lesion was planned.

Sacroiliac joint was approached under image intensifier from lateral trans-gluteal approach. The gluteus maximus was split longitudinally to reach the lateral sacroiliac joint & a rectangle cortical window was achieved with the help of an osteotome. Pus was drained, joint curetted and a biopsy was taken. The left iliac region sinus was explored by General surgeon after elliptical excision of sinus. The track of sinus was near to ileacus muscle and anterior to sacroiliac joint. The pus was drained & biopsy taken from sinus too. Wounds were closed over drain. Intraoperative and postoperative period was uneventful and patient remained stable.

Histopathology

Biopsy revealed caseous material surrounded by clusters of epitheloid cells & few multinucleated giant cells with moderate lymphocytic infiltration suggestive of tubercular etiology. TB PCR was positive from biopsy. Patient was started on antitubercular treatment. He tolerated the antitubercular treatment and his general condition improved with significant healing of his sinus in two months.

Discussion

Isolated sacroiliac involvement is very rare. It usually presents as vague back pain. Plain radiographs are often inconclusive in early disease. Due to rarity of lesion, vague symptoms and non-conclusive X-rays the diagnosis is further delayed. Sacroiliac tuberculosis must be kept as a differential in all refractory low back pain particularly in endemic areas. MRI is very helpful in early diagnosis of disease. Tuberculosis of bone usually follows primary infection. The mycobacteria spread haematogenously at the time of the primary infection or, later, from a dormant primary site or from another extra-osseous secondary focus.

In our patient pelvic radiographs, bone scans and CT scan showed a localized lesion at the left sacroiliac joint. These methods of investigation give satisfactory results in the majority of patients with inflammatory disease, although they do not have the sensitivity to differentiate pyogenic from granulomatous sacroiliitis. Therefore an open biopsy is required with drainage of sinus and to confirm the diagnosis with the help of histological and microbiological findings.

In addition, significant clinical improvement after antitubercular treatment further supported the diagnosis of sacroiliac joint tuberculosis in our patient.