| Description |
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If the suppuration within the mastoid cavity begins to extend into the lateral cortex, edema of the skin behind the pinna (retroauricular edema) will develop.
As the edema increases, the postauricular sulcus is effaced, and the pinna is usually displaced forward.
If the empyema erodes through the lateral cortex of the mastoid, a subperiosteal abscess may develop in the retroauricular area midway between the tip of the mastoid process and Macewen's triangle.
In rare cases, a subperiosteal abscess may form on the medial surface of the mastoid tip and track down the sternomastoid fascia to appear in the neck (Bezold's abscess). |
