A 6-year-old child presents with a 10-day history of acute otitis media treated with amoxicillin. Over the past 3 days, he has developed postauricular pain, swelling, and erythema with anterior displacement of the pinna. On examination, the mastoid tip is tender and fluctuant. A plain mastoid X-ray (Schüller view) shows the finding marked **A** in the diagram. Which of the following best describes the pathological process occurring at this site?
A. Osteoclastic breakdown of bony septa between air cells with abscess formation (coalescent mastoiditis)
B. Subperiosteal abscess with intact mastoid architecture
C. Serous effusion in the mastoid air cells without bone destruction
D. Periostitis with intact air cell septation
Explanation
Why Osteoclastic breakdown of bony septa between air cells with abscess formation (coalescent mastoiditis) is right
The finding marked A — mastoid air cell opacification with septal loss — is the radiological hallmark of coalescent mastoiditis, the third stage in the pathogenesis of acute mastoiditis. This represents osteoclastic breakdown of the bony septa that normally separate air cells, allowing pus to accumulate and form an abscess. The loss of the normal "honeycomb" trabecular pattern on plain X-ray and the clinical presentation (postauricular pain, swelling, erythema, pinna displacement, fluctuance) are pathognomonic for coalescent disease requiring urgent surgical intervention. According to AAO-HNS 2024 and Scott-Brown's, coalescent mastoiditis is the stage that mandates cortical mastoidectomy.
Why each distractor is wrong
Serous effusion in the mastoid air cells without bone destruction: This describes the first stage (mastoid effusion) of acute mastoiditis, which shows opacification but preserved air cell septation. The diagram explicitly shows septal loss, ruling out this early stage.
Periostitis with intact air cell septation: This is the second stage of acute mastoiditis. Periostitis causes inflammation of the periosteum but does NOT cause osteoclastic breakdown of septa. The presence of septal loss in A indicates progression beyond periostitis.
Subperiosteal abscess with intact mastoid architecture: A subperiosteal abscess is the most common complication of coalescent mastoiditis but is a separate entity—it forms outside the mastoid cortex. The diagram shows intramastoid opacification with septal loss, not a collection beneath the periosteum.
High-YieldNEET PG
Mastoid air cell opacification + septal loss = coalescent mastoiditis = surgical emergency requiring cortical mastoidectomy.
AAO-HNS 2024; Scott-Brown's Otorhinolaryngology — Acute Mastoiditis pathogenesis and imaging
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