What is the diagnosis for a patient with suspected postseptal orbital cellulitis, involving the lacrimal gland and extending to the cavernous sinus, presenting with impaired vision, abnormal pupillary response, and limited extraocular movements?

Diagnosis: Complicated Postseptal Orbital Cellulitis with Intracranial Extension

This patient has complicated postseptal orbital cellulitis with lacrimal gland involvement and cavernous sinus extension, representing a life-threatening emergency requiring immediate hospitalization, IV broad-spectrum antibiotics, urgent MRI brain and orbits with contrast, and emergent multidisciplinary consultation with ophthalmology, otolaryngology, and neurosurgery. 1, 2

Clinical Diagnosis Confirmation

The constellation of impaired vision, abnormal pupillary response, and limited extraocular movements definitively indicates postseptal (orbital) cellulitis rather than preseptal disease. 1, 2

Key diagnostic features present:

• Impaired vision and abnormal pupillary response indicate optic nerve involvement or raised intraorbital pressure causing retinal artery compromise—both vision-threatening complications requiring emergent intervention 1
• Limited extraocular movements (ophthalmoplegia) suggests either direct orbital involvement or cavernous sinus thrombosis, the latter being potentially fatal 3, 1
• Lacrimal gland involvement is consistent with orbital cellulitis, as the lacrimal gland lies within the orbit and its involvement indicates postseptal disease 4
• Cavernous sinus extension represents intracranial spread and carries mortality risk from thrombosis, meningitis, or cerebral abscess 1, 5

Immediate Diagnostic Workup Required

MRI brain and orbits with and without IV contrast is the mandatory imaging study given the suspected intracranial extension to the cavernous sinus. 3 MRI provides superior soft-tissue resolution compared to CT for evaluating cavernous sinus involvement and intracranial complications. 3

Contrast-enhanced MRA should be added to the MRI protocol given the high suspicion for cavernous sinus thrombosis, as this provides additional vascular information beyond traditional MRI sequences. 3

While CT orbits with contrast is typically the initial imaging for suspected orbital cellulitis 1, 2, this patient's presentation with cavernous sinus involvement necessitates proceeding directly to MRI for more detailed assessment. 3

Critical Differential Considerations

Idiopathic Orbital Inflammatory Syndrome (IOIS) can mimic orbital cellulitis with similar orbital signs including lacrimal gland enlargement, extraocular muscle involvement, and proptosis, but is non-infectious and requires corticosteroids rather than antibiotics. 3, 1 However, given the severity of presentation with vision impairment and cavernous sinus involvement, infectious etiology must be presumed and treated emergently. 1

IgG4-related orbital disease accounts for a significant percentage of previously "idiopathic" orbital inflammation and can present with lacrimal gland enlargement. 3, 1 This remains a diagnosis of exclusion after infection is ruled out. 3

Invasive fungal sinusitis must be considered, particularly if the patient is immunocompromised, as this carries 50-80% mortality and requires aggressive surgical debridement. 1 A low threshold for suspecting fungal disease is essential given the morbidity. 3

Life-Threatening Complications Present

Cavernous sinus thrombosis is the most immediately life-threatening complication, presenting with ophthalmoplegia and potentially bilateral eye involvement if untreated. 1, 6, 5

Vision loss mechanisms in this patient include:

• Raised orbital pressure causing retinal artery occlusion 1
• Direct optic nerve injury from inflammation or compression 1, 2
• Superior ophthalmic vein occlusion 1

Intracranial extension can progress to meningitis, subdural empyema, epidural abscess, or cerebral abscess. 1, 6

Immediate Management Algorithm

Hospitalize immediately with IV broad-spectrum antibiotics covering Staphylococcus aureus (including MRSA given lacrimal gland involvement 4), Streptococcus species, and anaerobes. 1, 6 Polymicrobial infection occurs in 13% of cases, necessitating broad coverage. 6

Emergent ophthalmology consultation is mandatory to assess for orbital abscess requiring surgical drainage and to monitor for progressive vision loss. 1

Urgent otolaryngology consultation is required as the infection source is likely adjacent paranasal sinuses, and surgical drainage may be necessary. 3, 1

Neurosurgery consultation should be obtained given cavernous sinus involvement and risk of intracranial complications. 1

Critical Pitfalls to Avoid

Do not delay imaging when vision changes or ophthalmoplegia are present, as this can result in missed cavernous sinus thrombosis, meningitis, or brain abscess. 1

Do not wait 24-36 hours for antibiotic response before considering surgery when vision is already impaired—this patient requires immediate surgical evaluation given the presenting visual compromise. 6, 5

Do not assume all orbital inflammation is infectious—however, in this acute presentation with vision loss and cavernous sinus involvement, infectious etiology must be treated first. 3, 1

Monitor for bilateral eye involvement, which would strongly suggest cavernous sinus thrombosis given the venous connections between orbits. 1