A 5‑year‑old child with three days of viral upper respiratory infection now presents with swelling beneath the right eye; what is the most likely diagnosis and appropriate management?

Acute Bacterial Sinusitis with Preseptal Cellulitis

This 5-year-old most likely has acute bacterial sinusitis complicated by preseptal cellulitis, requiring immediate systemic antibiotic therapy and urgent evaluation to exclude orbital cellulitis.

Most Likely Diagnosis

The clinical presentation of viral URI symptoms for 3 days followed by infraorbital swelling strongly suggests acute bacterial sinusitis with preseptal cellulitis 1. This represents bacterial superinfection following viral URI, which is the most common predisposing factor for acute bacterial sinusitis in children 1.

Key Diagnostic Features Supporting This Diagnosis:

• Timing: Swelling developing after 3 days of cold symptoms fits the pattern of bacterial superinfection complicating viral URI 1
• Location: Infraorbital (under the eye) swelling is characteristic of maxillary sinusitis with preseptal extension 1
• Age: At 5 years old, the maxillary and ethmoid sinuses are well-developed and prone to bacterial infection 1

Critical Immediate Assessment Required

You must immediately differentiate preseptal cellulitis from orbital cellulitis, as orbital cellulitis is a vision- and life-threatening emergency 2, 3.

Examine for These Red Flags Indicating Orbital Cellulitis:

• Proptosis (forward displacement of the globe) 2, 3
• Impaired extraocular movements or diplopia 2, 4, 3
• Reduced visual acuity 4
• Relative afferent pupillary defect 3
• Severe pain with eye movement 3

If ANY of these signs are present, obtain contrast-enhanced CT scan of orbits and sinuses immediately 2. Orbital cellulitis, subperiosteal abscess, or orbital abscess require emergency ENT/ophthalmology consultation and IV antibiotics 2, 3.

Management Algorithm

If Preseptal Cellulitis Only (No Orbital Signs):

Initiate systemic antibiotics immediately 1, 2. The American Academy of Pediatrics recommends treatment based on clinical presentation without imaging in uncomplicated cases 1.

Antibiotic Selection:

• First-line: Amoxicillin-clavulanate (high-dose amoxicillin component: 80-90 mg/kg/day divided twice daily) 1
• This covers Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis 5

Clinical Monitoring:

• Reassess at 48-72 hours for improvement 1, 4
• If worsening or no improvement, consider antibiotic-resistant organisms and obtain imaging 1, 3
• Do NOT obtain imaging initially if no orbital signs present, as imaging does not change management in uncomplicated acute bacterial sinusitis 1

If Orbital Signs Present:

1. Obtain contrast-enhanced CT orbit and sinuses emergently 2, 3
2. Start IV antibiotics immediately (do not wait for imaging) 3
3. Consult ENT and ophthalmology emergently 2, 3
4. Consider endoscopic sinus surgery if subperiosteal or orbital abscess identified 3

Common Pitfalls to Avoid

Do Not Confuse with Viral Conjunctivitis:

While adenoviral conjunctivitis can cause eyelid swelling, it presents with bilateral involvement, watery discharge, follicular reaction, and preauricular lymphadenopathy 1, 6. Unilateral infraorbital swelling following URI is sinusitis with preseptal cellulitis until proven otherwise 3.

Do Not Delay Treatment:

• Never treat preseptal cellulitis with topical antibiotics alone 2
• Oral antibiotics for preseptal cellulitis are insufficient if orbital involvement develops 3
• Delays in recognizing orbital cellulitis can lead to vision loss, intracranial extension (meningitis, epidural/subdural empyema, brain abscess), and death 1, 3

Do Not Over-Image:

• Imaging is not indicated for uncomplicated acute bacterial sinusitis without orbital signs 1
• Up to 68% of children with viral URI have sinus abnormalities on imaging, making radiographic findings alone unreliable for diagnosis 1

Why This Matters for Morbidity and Mortality

Untreated or inadequately treated sinusitis with orbital extension carries significant morbidity and mortality 1. Intracranial complications include meningitis, encephalitis, epidural empyema, subdural empyema, brain abscess, and cavernous sinus thrombosis 1. Low socioeconomic status and poor healthcare access correlate with higher rates of these complications 1.

Early recognition and appropriate systemic antibiotic therapy prevent progression from preseptal to orbital cellulitis, preserving vision and preventing life-threatening complications 3.