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Summary Table

Feature	Detail
Risk Factors	Untreated or inadequately treated acute otitis media (AOM), chronic suppurative otitis media (CSOM), immunocompromised states, delayed mastoiditis management, cholesteatoma
Etiology	Coalescent mastoiditis with cortical bone erosion; common organisms include Streptococcus pneumoniae, Streptococcus pyogenes, Staphylococcus aureus, Pseudomonas aeruginosa (especially in CSOM), and anaerobes
Patient Presentation	History of ear infection or ear discharge followed by progressive swelling in the neck or temporal region, with fever, otalgia, and worsening systemic symptoms
Classic Physical Exam	Bezold: deep neck mass along the SCM with torticollis. Luc: swelling above and anterior to the ear in the temporal region. Citelli: swelling behind the ear extending into the upper posterior neck at the digastric triangle
Key Diagnostic Results	CT temporal bone with IV contrast showing mastoid coalescence and extracranial abscess collection in the corresponding anatomical compartment
Management	IV broad-spectrum antibiotics + cortical mastoidectomy + incision and drainage of the abscess
Keywords	"Ear discharge for weeks, now neck swelling" (Bezold), "Post-auricular and temporal swelling" (Luc), "Swelling behind the mastoid tip extending to the neck" (Citelli), torticollis after otitis media, coalescent mastoiditis

1. Pathophysiology

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.

2. Classification and Clinical Manifestation

Abscess	Site of Cortical Erosion	Anatomical Space	Clinical Swelling	Distinguishing Feature
Bezold	Medial cortex of the mastoid tip	Deep to the SCM, deep neck fascial planes	Neck mass along the anterior border of the SCM	Torticollis (head tilted to the affected side); deep swelling that may be subtle externally
Luc	Outer cortex at the zygomatic root / zygomatic air cells	Temporal fossa, deep to the temporalis muscle or subperiosteal	Swelling above and anterior to the ear, in the temporal region	Also called zygomatic abscess; located superior to the ear, not behind it
Citelli	Posterior surface of the mastoid tip at the digastric groove	Digastric triangle, posterior triangle of the neck	Swelling posterior and inferior to the mastoid, extending into the upper neck	Pus follows the posterior belly of the digastric; distinct from the typical post-auricular subperiosteal abscess

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.

3. Diagnostic Workup

Test	Role	Expected Finding
Otoscopic examination	Initial assessment	Bulging or perforated tympanic membrane, purulent otorrhea, sagging of the posterosuperior canal wall
CT temporal bone with IV contrast	Best initial imaging and primary diagnostic tool	Coalescence of mastoid air cells (loss of bony septa), cortical erosion at the corresponding surface, rim-enhancing fluid collection in the neck (Bezold), temporal fossa (Luc), or digastric region (Citelli)
MRI with gadolinium	Adjunct when intracranial extension is suspected	Better soft tissue delineation; evaluates for concurrent sigmoid sinus thrombosis, epidural abscess, or brain abscess
Blood cultures and culture of abscess aspirate	Identify causative organism	Guides targeted antibiotic therapy; polymicrobial infections common in CSOM-related cases

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.

4. Management and Treatment

Phase	Intervention	Details
Acute stabilization	IV broad-spectrum antibiotics	Empiric coverage targeting gram-positive cocci, Pseudomonas, and anaerobes. A common regimen: ceftriaxone 2 g IV every 12 hours (or ceftazidime if Pseudomonas coverage is prioritized) + metronidazole 500 mg IV every 8 hours. Adjust based on culture results.
Source control (ear)	Cortical mastoidectomy	Mandatory. Removes the coalescent mastoid, the source of ongoing infection. Performed urgently, not electively. Also serves as the definitive procedure for the mastoid component.
Abscess drainage	Incision and drainage of the extracranial collection	Performed in the same operative session as mastoidectomy. The surgical approach varies by abscess location: neck incision along SCM for Bezold, temporal incision for Luc, post-auricular/neck approach for Citelli.
Post-operative	IV antibiotics continued for 2 to 4 weeks (or longer based on clinical response), with transition to oral antibiotics when improving	Regular wound care, repeat imaging if clinical improvement stalls

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.

5. Differential Diagnosis and Distractors

Differential Diagnosis	Why It Is Similar	Key Discriminator
Post-auricular subperiosteal abscess	Also a complication of mastoiditis with swelling near the ear	Swelling is directly over the lateral mastoid and pushes the auricle outward and downward; does not extend into the neck, temporal fossa, or digastric triangle
Parapharyngeal abscess	Deep neck infection with fever, neck stiffness, and trismus	No preceding otitis media or mastoiditis; usually follows pharyngitis or dental infection. CT shows collection in the parapharyngeal space, not tracking from the mastoid
Deep neck space infection (Ludwig angina, retropharyngeal abscess)	Neck swelling with systemic sepsis	Odontogenic or pharyngeal origin; no ear complaints, no coalescent mastoiditis on CT
Cervical lymphadenitis / suppurative lymph node	Neck mass with fever in a patient who may also have ear symptoms	Imaging shows an enlarged lymph node with central necrosis, but the mastoid architecture is intact; no cortical erosion
Lateral sinus thrombosis	Complication of mastoiditis with high fever and toxicity ("picket-fence" fever pattern)	An intracranial complication, not an extracranial abscess. CT venography or MRI shows thrombus in the sigmoid/lateral sinus. No external abscess collection.
Temporal bone malignancy (e.g., squamous cell carcinoma)	Destructive process in the temporal bone with soft tissue extension	Typically elderly patients; chronic otorrhea unresponsive to treatment; no acute infectious prodrome. Biopsy confirms neoplasm.

6. Traps 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.

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