Sinus tract

Last revised by Dr Ali Alsmair on 16 Mar 2022

Sinus tracts are an abnormal connection between a fluid collection with a mucous mucosal surface and/or skin 1,2. It can result from acute or chronic processes and occasionally extend into the joints and bones 1.

The term sinus tract is non-specific; however, when used in soft tissue or bony infections, it generally delineates the extent of infection 1.

Sinus tracts can develop 2:

  • spontaneously
  • secondary to iatrogenic injury (e.g. surgical incision)
  • post-traumatic
  • underlying collection or necrotic material (e.g. necrotizing pancreatitis)
  • secondary to infective bone foci (e.g. osteomyelitis)
  • secondary to infected membranous sacs (e.g. chronic empyema)
  • secondary to an underlying foreign body (e.g. shrapnel)

Squamous cell carcinoma may rarely develop within the chronic sinus tracts in cases of chronic osteomyelitis 3,4.

Direct visualization of the sinus tract, its ramifications, and extent can be done using radio-opaque contrast material under fluoroscopic guidance.

Active tracts are typically 1:

  • T1: hypointense
  • T2/T2FS: hyperintense
  • T1 C+: tram-track pattern of peripheral enhancement

Chronic fibrosed sinus tracts typically demonstrate T1 and T2 hypointense signals without contrast enhancement 1.

The radiological report should contain a description of the following:

  • presence, location, size, and ramifications of the sinus tract
  • associated findings
    • presence, location, and size of the underlying abnormal collection
    • extension into the joint or bone

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