A 35-year-old man from rural India presents with progressive thoracic back pain and kyphotic deformity. Imaging reveals destruction of two adjacent vertebral bodies with preservation of the intervertebral disc. MRI shows paravertebral abscess and cord compression. Which of the following is NOT a characteristic feature of Pott disease?

Explanation

## Characteristic Features of Pott Disease **Key Point:** Pott disease (spinal tuberculosis) has a distinctive pattern of vertebral involvement that differentiates it from pyogenic spondylodiscitis and other spine pathologies. ### Typical Pattern of Vertebral Involvement | Feature | Pott Disease | Pyogenic Spondylodiscitis | |---------|--------------|-------------------------| | **Primary site** | Vertebral body metaphysis (near endplate) | Intervertebral disc | | **Disc involvement** | Late (secondary) | Early (primary) | | **Number of vertebrae** | Often 2+ adjacent levels | Usually single level | | **Abscess formation** | Cold abscess (chronic, painless) | Warm abscess (acute) | ### Pathogenesis of Vertebral Destruction in Pott Disease 1. **Hematogenous seeding** → vertebral body metaphysis (rich vascular supply) 2. **Slow, progressive destruction** → caseating granulomas 3. **Disc preserved early** → TB does not produce disc enzymes like pyogenic bacteria 4. **Late disc involvement** → secondary to vertebral body collapse and kyphosis 5. **Paravertebral abscess** → tracks along fascial planes (psoas, paraspinal) **High-Yield:** The **preservation of the intervertebral disc in early Pott disease** is a classic distinguishing feature from pyogenic infection, where the disc is involved early and destroyed rapidly. **Warning:** Option 3 describes the pattern of **pyogenic spondylodiscitis**, NOT Pott disease. In pyogenic infection, the disc is the primary site of involvement, with secondary vertebral body destruction — the reverse of TB. ### Clinical Correlates **Clinical Pearl:** The presence of a **large paravertebral abscess with minimal disc involvement** should raise suspicion for TB rather than pyogenic infection. **Mnemonic: POTT (Pott's Original TB Traits):** - **P**reserved disc (early) - **O**steitis of vertebral body (metaphysis) - **T**wo or more vertebrae - **T**racking abscess (cold, painless) [cite:Robbins 10e Ch 8]