In a patient with HIV infection presenting with an iris lesion, what is the differential diagnosis, recommended workup, and appropriate treatment plan?

IRIS in HIV: Immune Reconstitution Inflammatory Syndrome

In HIV patients presenting with iris lesions, the differential diagnosis must distinguish between opportunistic infections (particularly CMV retinitis, syphilis, and fungal infections), immune reconstitution inflammatory syndrome (IRIS), and less commonly, malignancies or autoimmune conditions—with immediate ophthalmologic consultation and targeted antimicrobial therapy being critical to prevent irreversible vision loss.

Differential Diagnosis

Primary Infectious Causes

CMV Retinitis (most common in CD4 <50 cells/µL):

• Presents with floaters, visual field defects, and characteristic "pizza pie" or "cottage cheese and ketchup" retinal appearance
• Can cause iris involvement through immune recovery uveitis (a form of IRIS) 1
• Associated with increased mortality if untreated 1

Syphilis:

• Can present as vascularized iris masses, anterior uveitis, or bilateral uveitis 2, 3
• More severe and difficult to recognize in HIV patients 3
• May be the sentinel manifestation requiring urgent recognition 2

Fungal Infections:

• Candida albicans can cause anterior uveal abscesses with hypopyon and pupillary membranes 4
• Rare but documented in HIV-positive patients with severe immunosuppression 4

Varicella Zoster Virus:

• Can cause recurrent anterior uveitis with iris heterochromia and granulomatous keratic precipitates 5
• May be misdiagnosed as Fuchs' uveitis 5

IRIS Manifestations

Immune Recovery Uveitis:

• Occurs when ART restores immune function in patients with pre-existing CMV retinitis 1
• Complications include retinal detachment and vision loss, more common with larger CMV lesions 1
• Paradoxical worsening despite appropriate antimicrobial therapy 6

Recommended Workup

Immediate Assessment (within 24 hours):

Ophthalmologic Evaluation:

• Dilated funduscopic examination by ophthalmologist
• Document location and extent of lesions (proximity to optic nerve/fovea determines urgency) 1
• Laser flare photometry if available to quantify inflammation 5

Laboratory Testing:

• CD4+ T-cell count and HIV viral load (assess immune status and ART effectiveness) 1
• Syphilis serology (RPR/VDRL and treponemal-specific tests) 2, 3
• CMV PCR from blood (correlates with end-organ disease risk) 1
• Blood cultures if systemically ill

Imaging:

• Chest X-ray to assess for pulmonary involvement 7
• Consider MRI with contrast if CNS involvement suspected 8

Additional Testing Based on Findings:

• If anterior chamber involvement: Aqueous or vitreous tap for culture, PCR, and cytology
• If systemic symptoms: Fecal occult blood, endoscopy for GI involvement 7
• If iris mass present: Biopsy may be necessary to exclude lymphoma or Kaposi sarcoma 8, 7

Treatment Algorithm

For CMV Retinitis:

Sight-Threatening Lesions (adjacent to optic nerve/fovea):

• Ganciclovir intraocular implant PLUS oral valganciclovir (superior to IV ganciclovir alone for preventing relapse) 1
• Consider immediate intravitreous ganciclovir injection while arranging implant placement 1

Small Peripheral Lesions:

• Oral valganciclovir alone may be adequate 1
• Continue for 3-6 months until ART achieves immune recovery 1

Critical Point: Even small peripheral lesions should receive systemic anti-CMV therapy because anti-CMV treatment decreases mortality in immunocompromised patients 1

For Syphilitic Uveitis:

• Intravenous penicillin G or ceftriaxone (ocular syphilis requires neurosyphilis treatment regimen) 2
• Continue for 10-14 days
• Early recognition prevents permanent vision loss 2

For Fungal Infections:

• Pars plana vitrectomy with abscess aspiration for anterior uveal abscesses 4
• Systemic antifungal therapy based on culture results
• Intravitreal antifungal injection may be necessary

ART Management:

Initiate or Continue ART in Most Cases:

• Start ART in treatment-naïve patients with CMV retinitis, GI disease, or pneumonitis 1
• No data suggest ART worsens these conditions 1

Exception - Consider Delaying ART:

• In CMV neurologic disease, delay until clinical improvement to avoid localized IRIS-related morbidity 1
• This is the ONLY scenario where ART delay is recommended 1

IRIS Management:

If IRIS Develops:

• Continue ART (immune recovery is ultimately beneficial) 6
• Continue antimicrobial therapy for underlying infection 6
• Add corticosteroids for severe inflammatory response (ophthalmologist-guided dosing)
• Close monitoring for complications (retinal detachment, vision loss) 1

Critical Pitfalls to Avoid

1. Do not delay ophthalmologic consultation: Vision-threatening progression can occur within days 1

2. Do not withhold anti-CMV therapy in ART-naïve patients: Even with planned ART initiation, the 3-6 month delay to immune recovery risks vision loss and increased mortality 1

3. Do not mistake iris heterochromia for Fuchs' uveitis: In HIV patients, this more likely represents infectious uveitis (VZV, syphilis) requiring antimicrobial therapy 5

4. Do not treat CMV viremia without end-organ disease: Pre-emptive therapy is not recommended 1

5. Do not assume single pathology: HIV patients can have multiple concurrent infections or IRIS unmasking underlying infections 6

6. Do not use systemic therapy alone for sight-threatening CMV lesions: Combination of intraocular implant plus systemic valganciclovir is superior 1

Monitoring Requirements

• Weekly ophthalmologic exams during acute phase
• CD4+ counts and HIV viral load every 3-6 months to assess immune recovery 1
• Patient education on self-monitoring for floaters and visual changes 1