Tuberculous Osteomyelitis of The Pubic Symphysis – a Case Report of a Rare Entity Mimicking Spondyloarthritis

Tuberculosis (TB) osteomyelitis of the pubic symphysis is an extremely rare diagnosis. Axial spondyloarthritis (SpA) is characterized by inflammatory back pain and enthesitis, and involvement of pubic symphysis is very unusual at presentation. A 36-year-old female patient with a history of inflammatory back and pubic pain was referred to Rheumatology. She had a pelvic magnetic resonance imaging (MRI) suggestive of osteitis pubis. She was started on etoricoxib 90mg/day as axial spondyloarthritis was suspected, with no improvement. Pelvic MRI was repeated and showed osteomyelitis of the iliopubic branches. An ultrasound-guided biopsy was performed, and culture was positive for Mycobacterium tuberculosis. Further imaging studies revealed small cavitations and several centrilobular micronodules with a tree-in-bud pattern in the upper lung lobes and in the upper segment of the lower left lobe. She was started on anti-tuberculous treatment for 1 year and had a good clinical and radiological response. TB osteomyelitis of the pubic symphysis is a rare entity and has seldom been reported. However, this is the first case, to our knowledge, where the clinical picture mimicked an itself unusual presentation of SpA.