What is the differential diagnosis (ddx) for a patient with an upper eyelid skin rash, eye pain, and decreased vision, with a clear cornea?

Differential Diagnosis: Upper Eyelid Rash with Eye Pain and Decreased Vision (Clear Cornea)

Immediate Priority: Rule Out Vision-Threatening Emergencies

This presentation with eye pain and decreased vision requires urgent ophthalmology evaluation within 24 hours, even with a clear cornea, as the combination of these symptoms with eyelid involvement suggests serious underlying pathology that may not yet manifest corneal changes. 1

The presence of moderate-to-severe pain with visual changes constitutes red flag features requiring same-day ophthalmology referral, regardless of corneal appearance. 1

---

Most Critical Diagnoses to Consider First

Herpes Zoster Ophthalmicus (Shingles)

• Presents unilaterally with vesicular dermatomal rash or ulceration of upper eyelid, conjunctival injection, watery discharge, and follicular reaction 1
• Eye pain and decreased vision can occur from uveitis, keratitis, or optic neuritis even before corneal involvement is visible 1
• Can progress to corneal anesthesia, scarring, and permanent vision loss if untreated 1
• Requires immediate ophthalmology referral and systemic antiviral therapy 1

Herpes Simplex Virus (HSV) Keratouveitis

• Usually presents unilaterally with eyelid involvement, bulbar conjunctival injection, and palpable preauricular lymphadenopathy 1
• Can cause stromal keratitis and uveitis leading to vision loss even with initially clear cornea 1
• Progresses to corneal scarring, perforation, and permanent vision loss without treatment 1
• Immediate ophthalmology referral required for suspected HSV with vesicles or vision changes 1

Orbital or Preseptal Cellulitis

• Orbital cellulitis presents with proptosis, ophthalmoplegia, vision loss, and fever—requires emergent hospitalization and IV antibiotics 1, 2
• Preseptal cellulitis shows eyelid erythema, edema, and tenderness WITHOUT proptosis, painful eye movements, or vision changes 1, 2
• However, vision loss in this case suggests orbital involvement or progression—immediate hospitalization indicated 2
• Obtain contrast-enhanced CT of orbits and sinuses urgently 2

---

Other Important Differential Diagnoses

Wegener's Granulomatosis (Granulomatosis with Polyangiitis)

• Can present with upper eyelid ulceration, orbital mass, ulcerative keratitis, and ocular pain 3
• Vision loss occurs from orbital involvement, uveitis, or optic nerve vasculitis 3
• May present as limited form without systemic manifestations initially 3
• Biopsy shows necrosis, granulomatous inflammation, and vasculitis 3

Sebaceous Carcinoma

• Can masquerade as chronic unilateral blepharoconjunctivitis resistant to treatment 1, 2
• Biopsy indicated for unifocal recurrent lesions, resistance to therapy, focal lash loss, or chronic presentation unresponsive to treatment 1, 2
• Vision loss can occur from direct tumor invasion or secondary inflammation 2

Severe Allergic Contact Dermatitis with Secondary Complications

• Upper eyelid is highly susceptible to contact allergens (cosmetics, metals, topical medications, artificial nails) 4, 5
• Allergic contact dermatitis accounts for 43-53% of eyelid dermatitis cases in patch-tested patients 4
• However, vision loss is NOT typical of simple contact dermatitis—suggests secondary infection, uveitis, or alternative diagnosis 4, 5

Atopic Keratoconjunctivitis (Severe)

• Chronic inflammatory keratoconjunctivitis with eyelid and periorbital skin involvement 6
• Can cause punctate epithelial erosions, corneal vascularization, and pannus formation 6
• Vision loss from corneal ulcers, infections, or cataract formation 6
• High risk of herpes simplex keratitis or keratouveitis in atopic patients 6

Cutaneous Leishmaniasis (Endemic Regions)

• Presents with bilateral upper eyelid erythema, induration, and blepharitis progressing to ulcerative nodules 7
• Must be considered in endemic regions with chronic eyelid swelling 7
• Diagnosis confirmed by cutaneous smear and biopsy showing amastigotes in macrophages 7

---

Diagnostic Algorithm

Step 1: Assess for Red Flags Requiring Emergency Intervention

• Check for proptosis, painful/impaired eye movements, fever, or systemic toxicity 1, 2
• If ANY present: immediate hospitalization, contrast-enhanced CT orbits/sinuses, IV antibiotics, urgent ophthalmology/ENT/ID consultation 2

Step 2: Examine Eyelid Rash Characteristics

• Vesicular dermatomal pattern → HSV/VZV → immediate ophthalmology referral and systemic antivirals 1
• Ulcerative nodules in endemic area → consider leishmaniasis, obtain biopsy 7
• Chronic unilateral resistant lesion → biopsy to rule out sebaceous carcinoma 1, 2

Step 3: Perform Fluorescein Staining

• Mandatory in every case to detect corneal involvement not clinically apparent 1
• Dendritic pattern → HSV keratitis 1
• Punctate epithelial keratopathy → multiple etiologies including atopic disease 6

Step 4: Check Visual Acuity, Pupil Reactivity, and Extraocular Movements

• Any abnormality with eyelid rash and pain requires same-day ophthalmology evaluation 1

Step 5: Consider Systemic Workup

• ANCA testing if orbital mass or systemic vasculitis suspected 3
• Patch testing if chronic dermatitis without vision-threatening features 4, 5

---

Critical Management Pitfalls to Avoid

• Never dismiss vision loss as "just dermatitis"—this combination demands urgent ophthalmology evaluation 1
• Do not delay antiviral therapy if HSV/VZV suspected—permanent vision loss can occur rapidly 1
• Always perform fluorescein staining even if cornea appears clear on gross examination 1
• Do not treat presumed "preseptal cellulitis" with oral antibiotics alone if vision is decreased—this suggests orbital involvement requiring hospitalization 2
• Biopsy any chronic unilateral eyelid lesion resistant to treatment to rule out malignancy 1, 2