CASE 15

By: Dr. Sattam Lingawi and Dr. Alaa Al-Turkustani

HISTORY: 69-year-old female patient known case of breast cancer presented to the hospital with neck pain radiating to the left arm.

What are your findings?

What is the differential diagnosis?

FINDINGS:

Fig 1 sagittal T1 SE demonstrating C6 and C7 vertebral body Low signal intensity.

Fig 2 sagittal T2 SE demonstrating C6/7 intervertebral disc bright signal intensity.

Fig 3 sagittal enhanced T1 SE with Fat saturation demonstrating significant abnormal enhancement within the affected vertebral bodies with associated anterior paraspinal enhancement.

DIFFERENTIAL DIAGNOSIS:

• Spondylodiscitis.

• Metastasis.

• Modic type I degenerative change.

DIAGNOSIS:

Spondylodiscitis with Brucellae spp.

PEARLS AND DISCUSSION:

Spondylodiscitis is characterised by infection involving the intervertebral disc and adjacent vertebrae.

Risk factors

• Remote infection (present in ~25%).

• Spinal instrumentation or trauma.

• Intravenous drug use.

• Immunosuppression.

• Long-term systemic administration of steroids.

• Advanced age.

• Diabetes mellitus.

• Organ transplantation.

• Malnutrition.

• Cancer.

Etiology

• Staphylococcus aureus (most common; 60%).

• Streptococcus viridans (IVDU, immunocompromised).

• Gram-negative organisms, e.g. Enterobacter spp, E. coli.

• Mycobacterium tuberculosis.

• Less common agents are:

  • Fungal:

    §  Cryptococcus neoformans.

    §  Candida species.

    §  Histoplasma capsulatum.

    §  Coccidioidesimmitis.

  • Brucellae spp.

MRI is the imaging modality of choice due to very high sensitivity and specificity. It is also useful in differentiating between pyogenic infection, tuberculous and fungal infections or a neoplastic process.

Signal characteristics include:

• T1

  • Low signal in disc space (fluid).

  • Low signal in adjacent endplates (bone marrow oedema).

• T2: (fat sat or STIR especially useful):

  • High signal in disc space (fluid).

  • High signal in adjacent endplates (bone marrow oedema).

  • Loss of low signal cortex at endplates.

  • High signal in paravertebral soft tissues.

• T1 C+ (Gd)

  • Peripheral enhancement around fluid collection(s).

  • Enhancement of vertebral endplates.

  • Enhancement of perivertebral soft tissues.

  • o    Enhancement around low-density center indicates abscess formation (hard to distinguish inflammatory phlegmon from abscess without contrast).

Main findings in the differential diagnosis of spondylodiscitis.

	Pyogenic	Tuberculous
Vertebral body enhancement	Homogeneous	Heterogeneous
Intervertebral disc	Early involvement	Relatively spared
Vertebral involvement	Segmental	Multisegmental

FURTHER READING:

1. Cristiano Gonzaga de Souza and Emerson Leandro Gasparetto, Pyogenic and tuberculous discitis: magnetic resonance imaging findings for differential diagnosis. Radiol Bras. 2013 Mai/Jun;46(3):173–177

2. Kyu Yeol Lee, Comparison of Pyogenic Spondylitis and Tuberculous Spondylitis. Asian Spine Journal 2014;8(2):216-223