Antrochoanal polyp

Case contributed by Dr Ian Bickle


Patient with right sided nasal blockage. Endoscopy suggestive of a antrochonal polyp.

Patient Data

Age: 30 years
Gender: Male

Contiguous soft tissue in the right maxillary sinus extending into the nasal canal and nasopharynx.

Widening of the bony ostium of the maxillary sinus.

The remainder of the paranasal sinuses are unremarkable.


The right maxillary sinus, posterior right nasal canal and nasopharynx are occupied with soft tissue. The tissue is contiguous, with widening of the sinus ostium.

The tissue is T1 isointense and intensely T2 hyperintense with heterogeneous, largely rim enhancement.

Case Discussion

An antrochoanal polyp (ACP) is a solitary polyp that arises within the maxillary sinus but passes through and enlarges the sinus ostium or more commonly an accessory ostium.

The nasal cavity is therefore extended posteriorly into the nasopharynx through the posterior chonae.

The MRI signal characteristics of this case are typical:

T1 - intermediate to low signal

  • T2
    • high homogeneous T2 signal
    • signal may vary if they are chronic and/or if fungal infection is present
  • T1 C+ (Gd) - peripheral enhancement is seen on post-contrast images.
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Case information

rID: 30002
Published: 13th Jul 2014
Last edited: 2nd Sep 2019
System: Head & Neck
Inclusion in quiz mode: Included

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