Abses Bezold, Luc, Citelli

01Pathophysiology

All three abscesses share a common origin: coalescent mastoiditis. In a normal mastoid, the air cell system is separated by thin bony septa. When acute or chronic otitis media progresses and infection reaches the mastoid, purulent material accumulates within the air cells. If left untreated, osteoclastic activity destroys the bony septa, merging individual air cells into a single cavity filled with pus. This is the coalescent phase.

Once the infection has consumed the internal architecture, pressure drives the purulent material outward. The direction of cortical erosion determines which abscess forms. The mastoid tip is a critical landmark because three different surfaces provide three different escape routes for pus.

Bezold abscess occurs when pus erodes through the medial cortex of the mastoid tip. This is the thinnest portion of the tip, located medial to the attachment of the sternocleidomastoid (SCM) muscle. Once pus breaches this surface, it tracks inferiorly deep to the SCM, dissecting along the fascial planes of the neck. Because the abscess is deep, it may not produce dramatic external swelling early on, which is why it is considered dangerous and often diagnosed late. The patient develops torticollis because the SCM becomes inflamed and goes into spasm, tilting the head toward the affected side.

Luc abscess forms when infection erodes through the outer cortex at the level of the zygomatic root or spreads through pneumatized zygomatic air cells. Pus tracks superiorly and anteriorly, collecting deep to the periosteum or beneath the temporalis muscle in the temporal fossa. This produces visible swelling above and in front of the ear. Some references also call this a zygomatic abscess or temporal abscess.

Citelli abscess results from erosion through the posterior surface of the mastoid tip at the digastric groove, where the posterior belly of the digastric muscle attaches. Pus enters the digastric triangle and may extend into the posterior triangle of the neck. The swelling characteristically appears behind and below the mastoid process, distinct from the typical post-auricular subperiosteal abscess that forms over the lateral mastoid cortex.

The key teaching point here is that all three are the same disease (coalescent mastoiditis) with different exit routes. The surface of erosion is the only variable, and it dictates the name, the clinical presentation, and the anatomical space requiring drainage.

02Classification and Clinical Manifestation

For comparison, the more common post-auricular subperiosteal abscess (often the first extracranial complication students learn) results from erosion through the lateral cortex of the mastoid. It pushes the auricle forward and downward. This is not Bezold, Luc, or Citelli.

03Diagnostic Workup

CT temporal bone with IV contrast is the workhorse investigation. It accomplishes two goals simultaneously: it confirms coalescent mastoiditis by showing destruction of the mastoid septae, and it localizes the abscess collection by demonstrating a rim-enhancing fluid pocket in the relevant anatomical compartment. The direction of the collection on axial and coronal cuts is what allows you to name the abscess type.

You order CT rather than MRI as the first-line study because CT provides superior bony detail to show exactly where the cortex has eroded. However, if the clinical picture suggests concurrent intracranial complications (altered mental status, focal neurologic deficits, high spiking fevers with rigors suggesting venous sinus involvement), you add MRI with gadolinium to evaluate the posterior fossa, dural surfaces, and sigmoid sinus.

Audiometry is not part of the acute workup but may be relevant later; conductive hearing loss is expected given the underlying middle ear pathology.

04Management and Treatment

The critical management principle is that antibiotics alone are insufficient. These are walled-off abscess collections, and the mastoid itself is a bony reservoir of infection. You must perform cortical mastoidectomy plus drainage. This is the "next best step" the exam tests: a student who selects "continue IV antibiotics and observe" is making the wrong choice.

If cholesteatoma is the underlying cause of chronic mastoiditis leading to the abscess, a modified radical or radical mastoidectomy may be needed instead of a simple cortical procedure, depending on the extent of disease.

Contraindications and adjustments: in patients with penicillin allergy, substitute a fluoroquinolone (ciprofloxacin) or carbapenem. In patients with renal impairment, dose-adjust metronidazole and monitor levels.

05Differential Diagnosis and Distractors

06Traps and High-Yield Pearls

The most common trap with these three abscesses is name-to-anatomy mismatch. Students often memorize the names without firmly linking each one to its erosion site and clinical presentation. On the exam, the vignette will not say "Bezold abscess"; it will describe a patient with weeks of ear discharge who now presents with a deep neck mass and torticollis. You are expected to recognize the pattern.

A second trap is confusing Bezold abscess with a post-auricular subperiosteal abscess. The subperiosteal abscess is far more common and pushes the pinna forward; Bezold does not cause auricular displacement because the pus tracks medially and inferiorly into the neck, not laterally.

The third trap involves management sequencing. Students may select IV antibiotics as the definitive answer. The exam consistently rewards the candidate who recognizes that a formed abscess in the setting of coalescent mastoiditis requires surgical intervention (mastoidectomy + drainage), not prolonged medical therapy alone.

The core competency being tested is your ability to (1) recognize extracranial complications of mastoiditis based on the anatomical description in the vignette, (2) correctly name the abscess, and (3) commit to surgical management as the definitive treatment.