Primary Tuberculous Osteomyelitis of the Proximal Tibia Presenting as Chronic Osteomyelitis: A Diagnostic Challenge...

Tuberculous involvement of long bones is an uncommon form of extrapulmonary tuberculosis (TB) and frequently poses a diagnostic dilemma because of its indolent presentation and non-specific imaging features. Tibial tuberculous osteomyelitis is particularly rare and may closely mimic subacute pyogenic osteomyelitis or Brodie's abscess, especially in immunocompetent individuals, leading to delayed diagnosis.

A 70-year-old immunocompetent male presented with a short duration of pain and swelling over the proximal tibia without constitutional symptoms. Radiographs showed a lytic metaphyseal lesion with cortical thinning, while magnetic resonance imaging revealed an intramedullary abscess cavity with surrounding marrow edema and minimal soft-tissue extension, suggestive of subacute osteomyelitis. Routine bacterial cultures were negative. Intraoperative aspirate tested positive for Mycobacterium TB on cartridge-based nucleic acid amplification test, confirming tuberculous osteomyelitis. The patient underwent intramedullary debridement, abscess drainage, and dead-space management with antibiotic-loaded calcium sulfate beads, followed by initiation of standard multidrug antitubercular therapy. Post-operative radiographs demonstrated adequate lesion clearance and maintained alignment, with progressive clinical improvement on follow-up.

Tibial tuberculous osteomyelitis should be considered in the differential diagnosis of metaphyseal lytic lesions resembling Brodie's abscess, even in immunocompetent patients with short-duration symptoms. Early biopsy and molecular diagnostics such as cartridge-based nucleic acid amplification tests are crucial for timely diagnosis. Combined surgical debridement and antitubercular therapy resulted in a favorable outcome in this patient. Further studies are required to determine the reproducibility of this approach.