Multifocal skeletal tuberculosis mimicking multiple myeloma and secondary bone metastasis: An unusual case scenario

Skeletal tuberculosis (TB) is rare, accounting for 1%–2% of all cases of TB with multifocal involvement being rarer. Bones most commonly involved are the spine, joints, shoulder girdle, sternum, pelvis, ribs, skull, and orbit. We hereby report such multifocal bone TB in a 58-year-old-male who presented with complaints of pelvic pain of 2 months' duration. Radiograph of pelvis showed lytic lesions left ilium. A differential diagnosis of multiple myeloma and secondary bone metastasis was initially thought of. Computed tomography scan, magnetic resonance imaging, and bone scan pointed toward metastatic bone involvement. Metastatic workup with positron emission tomography scan and myeloma workup were negative. Biopsy from the lytic bony lesion was done which revealed TB with Ziehl–Neelsen staining positive for acid-fast bacilli. He was diagnosed as a case of primary bone TB and was commenced on antitubercular therapy to which he responded significantly. This case is being reported to highlight its extreme rarity, the diagnostic and therapeutic challenges it presented, and the overall prognosis of this condition.