A 22-year-old man comes to the office due to 3 months of progressive back pain. He has also had intermittent subjective fever. The patient emigrated from Nepal for a master's program 6 months ago. He has no other medical conditions, takes no medication, and does not use tobacco, alcohol, or illicit drugs. Temperature is 38.3 C (100.9 F), blood pressure is 122/78 mm Hg, and pulse is 84/min. BMI is 19 kg/m². Tenderness is noted over the lumbar spine; flexion, extension, and rotation of the spine are limited due to pain and muscle spasm. MRI of the lower spine reveals partial destruction of the anterior portion of the L1-L3 vertebral bodies and a fluid collection beneath the anterior longitudinal ligament. Which of the following is the most likely diagnosis?

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This patient who recently emigrated from a tuberculosis-endemic region (Nepal) now has progressive back pain, intermittent fever, and vertebral bone destruction with an adjacent fluid collection (abscess), raising strong suspicion for Mycobacterium tuberculosis spondylitis (Pott disease). Primary tuberculosis infections are acquired via inhalation and cause localized pulmonary infection that is typically contained over weeks by the cell-mediated immune response. However, transient bacteremia can occur prior to containment and result in the hematogenous seeding of highly vascular organs (eg, spleen, liver, bones); the vertebrae are particularly likely to be affected due to their extensive venous plexuses. Pott disease typically occurs months to years following primary pulmonary infection. It is characterized by intermittent fever and slowly worsening pain in the lumbar or lower thoracic spine. The infection frequently spreads behind the anterior ligament to the adjacent vertebrae and intervertebral disc space, leading to contiguous bone destruction and abscess formation. (Choice A) Hodgkin lymphoma is often associated with intermittent fever but typically presents with regional adenopathy and/or a mediastinal mass. Vertebrae destruction and a fluid collection are not common features. (Choices B and C) Osteosarcoma is the most common primary bone tumor in young adults; however, the long bones are primarily affected, and imaging typically shows a lytic bone lesion. Rhabdomyosarcoma is a soft-tissue sarcoma that usually arises in the head/neck, genitourinary tract, or extremities; imaging usually reveals a soft-tissue mass. Neither is typically associated with fever and a fluid collection; these features make an infectious process far more likely. (Choice D) Staphylococcus aureus is the most common cause of spinal epidural abscess. Although the radiographic appearance can be similar to Pott disease, most cases arise in the setting of intravenous drug use, hematogenous spread of a distant infection (eg, endocarditis), or direct inoculation during a spinal procedure. This patient's recent emigration from a tuberculosis-endemic area makes Pott disease more likely. Educational objective: Mycobacterium tuberculosis spondylitis (Pott disease) is usually the result of hematogenous seeding of vertebrae from primary pulmonary infection. Manifestations typically arise months or years later (due to reactivation) and include chronic, progressive back pain, fever, and radiographic evidence of vertebral bone destruction and fluid collection. __________ References: Spinal tuberculosis: a review. (http://www.ncbi.nlm.nih.gov/pubmed/22118251)

A 22-Year-Old Man Comes to the Office Due to 3