Acute epiglottitis is acute inflammation and edema of the epiglottis and supraglottic structures (aryepiglottic folds, arytenoids, valleculae). While Haemophilus influenzae type B was the most common pathogen in pre-vaccination children, various pathogens (Streptococcus, Staphylococcus, Haemophilus non-typeable) now cause it predominantly in adults. It can rapidly progress to complete airway obstruction — requiring emergent airway management. The 'thumb sign' (thickened epiglottis) on lateral neck radiograph is the classic finding, while contrast-enhanced CT is the gold standard for diagnosis and complication assessment.
Age Range
2-65
Peak Age
45
Gender
Male predominant
Prevalence
Uncommon
Acute epiglottitis begins when bacterial pathogens infect the epiglottic mucosa. The inflammatory cascade — neutrophil infiltration, cytokine release, increased vascular permeability — creates rapidly spreading edema and cellulitis in the epiglottis and surrounding supraglottic structures. The anatomical structure of the epiglottis makes this process dangerous: since the epiglottic mucosa is tightly adherent to the underlying cartilage, edema fluid accumulates on the lingual surface, pushing the epiglottis posteriorly and inferiorly to narrow the airway lumen. The aryepiglottic folds contain loose areolar tissue, so edema spreads very rapidly there. In advanced cases, supraglottic abscess may form — liquefaction occurs in necrotic tissue. On imaging: edema reflects as high signal on T2, low density on CT; inflammatory hyperemia creates diffuse mucosal enhancement; if abscess develops, central low density + rim enhancement pattern is seen. Airway lumen diameter can narrow from the normal 5-7mm to 2-3mm — critical airway compromise.
Loss of the normal thin leaf shape of the epiglottis, taking on a rounded and thickened 'thumb' appearance on lateral neck radiograph or sagittal CT reformat. While normal epiglottic thickness is <3mm, it reaches >7mm in epiglottitis. Pathognomonic finding.
On contrast-enhanced CT, the epiglottis is thickened 2-3 times its normal size and assumes a rounded appearance — the axial and sagittal correlate of the lateral radiograph 'thumb sign'. While the normal epiglottis appears as a thin leaf shape (2-3mm) on sagittal sections, it thickens to 7-10mm in inflammation. The epiglottic mucosa shows diffuse enhancement (inflammatory hyperemia). Due to edema, the epiglottic parenchyma shows low density. Sagittal reformat evaluation best demonstrates epiglottic thickness and airway lumen.
Report Sentence
The epiglottis is markedly thickened, measuring approximately __ mm (thumb sign). The aryepiglottic folds are edematous and thickened. The supraglottic airway lumen is narrowed (airway diameter approximately __ mm). Diffuse mucosal enhancement is seen. Findings are consistent with acute epiglottitis.
The aryepiglottic folds are bilaterally thickened and edematous, showing diffuse low-density soft tissue swelling. The valleculae may be fluid-filled or obliterated. Reactive edema may also be seen in prevertebral soft tissue. Oropharyngeal and hypopharyngeal mucosa may also be edematous and thickened (spread supraglottitis).
Report Sentence
The aryepiglottic folds are bilaterally thickened and edematous. The valleculae appear [obliterated/fluid-filled]. Findings are consistent with supraglottitis.
In complicated cases, a low-density collection + rim enhancement is seen within or around the epiglottis or aryepiglottic folds — supraglottic abscess formation. Unlike cellulitis, abscess contains a well-defined fluid collection. Gas bubbles suggest anaerobic infection. Extension of abscess to the paraglottic space, pre-epiglottic fat, or retropharyngeal space should be assessed.
Report Sentence
A __ x __ mm rim-enhancing hypodense collection is seen at the epiglottis/aryepiglottic fold level, consistent with supraglottic abscess formation. Gas bubbles [are present/are not identified].
Markedly increased signal is seen in the epiglottis and aryepiglottic folds on T2-weighted and STIR sequences — the free water content of edema fluid produces high T2 signal. Fat suppression on STIR makes edema signal more conspicuous. Due to loose tissue in the aryepiglottic folds, edema is very well demonstrated on MRI. Mildly hypointense or isointense appearance on T1.
Report Sentence
Markedly increased signal is seen in the epiglottis and aryepiglottic folds on T2/STIR sequences. The supraglottic structures are edematous and thickened. Findings are consistent with acute epiglottitis/supraglottitis.
On lateral neck radiograph, the epiglottis has changed from its normal thin leaf shape to a rounded, thickened 'thumb' shape — the classic 'thumb sign'. While normal epiglottic thickness is under 3mm, it exceeds 7mm in epiglottitis. The aryepiglottic folds are also thickened and the valleculae may be obliterated. Airway lumen width should be assessed on lateral radiograph.
Report Sentence
On lateral neck radiograph, the epiglottis is markedly thickened with positive 'thumb sign'. The supraglottic airway is narrowed. Consistent with acute epiglottitis; further evaluation with contrast-enhanced CT is recommended.
Criteria
Diffuse edema and enhancement, no fluid collection
Distinct Features
Diffuse low-density swelling and mucosal enhancement on CT, no focal collection or rim enhancement. Most common form. Usually responds adequately to antibiotic therapy.
Criteria
Focal hypodense collection + rim enhancement within epiglottis or aryepiglottic fold
Distinct Features
May require surgical drainage. Gas bubbles suggest anaerobic infection. Higher complication risk.
Criteria
Age 2-7 years, unvaccinated, rapid course, severe airway compromise
Distinct Features
Dramatically decreased after vaccination. More fulminant course, rapid obstruction risk due to small diameter of pediatric airway. Imaging usually performed after airway is secured.
Distinguishing Feature
Retropharyngeal abscess is localized in the retropharyngeal space; in epiglottitis, supraglottic structures are involved. Epiglottis is normal in retropharyngeal abscess.
Distinguishing Feature
In laryngeal trauma, cartilage fracture, emphysema, and hematoma are seen. In epiglottitis, no cartilage damage; inflammatory edema is predominant.
Distinguishing Feature
Reinke edema is at vocal cord level; epiglottis and supraglottic structures are normal. In epiglottitis, vocal cords are usually spared.
Urgency
emergentManagement
medicalBiopsy
Not NeededFollow-up
specialist-referralAcute epiglottitis is an airway emergency. Airway securing is the most urgent priority — intubation or tracheotomy in a controlled setting may be required. IV antibiotic therapy (3rd generation cephalosporin + anti-staphylococcal) is started immediately. Surgical drainage may be needed for abscess complication. Steroid therapy is controversial but used in some centers to reduce airway edema.
Acute epiglottitis is an airway emergency. Rapid airway securing is required (intubation or tracheotomy). IV antibiotic therapy is started. If abscess complication develops, surgical drainage may be needed.