Spondylodiscitis

18 years old male presented with low back pain. Patient denying any history of trauma.
Note indistinctness of affected end plates and altered signal of bone marrow which represents either marrow edema or infarction. Disc is also involved especially anteriorly. No subligamentous or perispinal collections. No abscess formation.
3 main categories for spinal infections:
1. Pyogenic.
2. Tuberculous.
3. Fungal [immunocompromised].
In pyogenic infection: early involvement of disc and more bone destruction.
In tuberculous infection: relative sparing of disc; usually subligamentous spread of infection with abscess formation; skipped vertebral lesions is possible due to subligamentous spread.
Note that metastasis sparing the disc.