What are the differential diagnoses and recommended treatment for a scalp bump and injected conjunctiva?

Bump on Sclera and Injected Conjunctiva: Differential Diagnosis and Treatment

For a bump on the sclera (bulbar conjunctiva) with conjunctival injection, the most critical first step is to distinguish between benign self-limited conditions and sight-threatening or life-threatening diagnoses that require urgent intervention.

Key Differential Diagnoses to Consider

Infectious Causes

Viral Conjunctivitis (Most Common)

• Adenoviral: Presents with bulbar conjunctival injection, watery discharge, follicular reaction, and often sequential bilateral involvement. Self-limited, resolving in 5-14 days 1
• HSV: Usually unilateral with watery discharge, mild follicular reaction, and may have vesicular eyelid lesions or dendritic keratitis 1
• Molluscum contagiosum: Unilateral follicular reaction with characteristic shiny, dome-shaped umbilicated lesions on eyelid skin 1

Bacterial Conjunctivitis

• Gonococcal: URGENT - marked eyelid edema, bulbar injection, significant purulent discharge, and preauricular lymphadenopathy. Critical to detect corneal infiltrate/ulcer which can lead to perforation 1
• Chlamydial (inclusion): Follicular conjunctivitis with distinctive follicles on bulbar conjunctiva and semilunar fold, chemosis, papillary hypertrophy 1
• Parinaud oculoglandular syndrome: Unilateral granulomatous follicular conjunctivitis with ipsilateral regional lymphadenopathy (preauricular/submandibular), fever, and conjunctival granulomas. Most commonly from cat scratch disease (Bartonella henselae) 1

Neoplastic Causes (Critical to Identify)

These can masquerade as chronic conjunctivitis:

• Ocular surface squamous neoplasia: Conjunctival hyperemia with papillomatous or sessile nodules, may be leukoplakic or gelatinous, often at limbal location with sentinel vessel. Associated with HPV, UV exposure, HIV 1
• Conjunctival lymphoma: Unilateral, painless, pink "salmon patch" fleshy swelling, often presents with chronic palpebral or bulbar follicles. Mobile and nonlobulated 1
• Melanoma: Painless, flat or nodular, brown or fleshy-pink lesion on bulbar conjunctiva. Associated with UV exposure, previous melanoma history 1
• Sebaceous carcinoma: Intense bulbar conjunctival injection with scarring, may have mucopurulent discharge. Often history of multiple chalazion excisions. Can be chronic and mistreated as unresponsive blepharoconjunctivitis 1

Non-Infectious Inflammatory Causes

• Allergic conjunctivitis: Typically bilateral with itching
• Superior limbic keratoconjunctivitis: May indicate underlying thyroid disorder 1
• Episcleritis/Scleritis: Localized nodular inflammation

Critical Red Flags Requiring Urgent Action

1. Corneal involvement (infiltrate, ulcer, or epithelial defect) - risk of perforation
2. Severe purulent discharge - consider gonococcal infection requiring immediate systemic therapy
3. Progressive or non-resolving lesion over weeks - suspect neoplasia
4. Unilateral chronic follicular conjunctivitis unresponsive to treatment - biopsy to rule out malignancy 1
5. Regional lymphadenopathy with conjunctival granulomas - consider Parinaud syndrome

Diagnostic Approach Algorithm

Step 1: Assess Acuity and Severity

• Acute onset (<2 weeks) with watery discharge → likely viral
• Acute with purulent discharge → bacterial (urgent if hyperacute)
• Chronic (>4 weeks) unresponsive to treatment → biopsy to exclude neoplasia

Step 2: Examine for Distinctive Features

• Follicles on bulbar conjunctiva/semilunar fold → chlamydial inclusion conjunctivitis
• Vesicular eyelid lesions → HSV or VZV
• Umbilicated eyelid lesions → molluscum
• Salmon patch appearance → lymphoma
• Nodular/papillomatous growth → squamous neoplasia
• Regional lymphadenopathy + granulomas → Parinaud syndrome

Step 3: Check Cornea with Fluorescein

• Dendritic pattern → HSV
• Punctate keratitis → multiple viral causes
• Infiltrate/ulcer → urgent treatment needed

Step 4: Laboratory Confirmation When Indicated

• Culture/PCR for suspected bacterial (especially gonococcal or chlamydial)
• Biopsy any chronic unresponsive lesion or suspicious mass 1

Treatment Recommendations

Viral Conjunctivitis

• Supportive care: cool compresses, artificial tears
• Strict hygiene to prevent spread
• Monitor for subepithelial infiltrates in adenoviral cases 1
• HSV with keratitis: topical antivirals (e.g., ganciclovir gel, trifluridine)

Bacterial Conjunctivitis

• Gonococcal (URGENT): Immediate systemic therapy with ceftriaxone 1g IM/IV, plus topical antibiotics. Admit if corneal involvement 1
• Chlamydial: Systemic azithromycin (1g single dose or doxycycline 100mg BID x 7 days) plus topical antibiotics 1
• Parinaud syndrome: Antimicrobials based on suspected organism (azithromycin for Bartonella) 1

Neoplastic Lesions

• Refer to ophthalmology immediately for biopsy and definitive diagnosis
• Treatment depends on histopathology: excision, topical chemotherapy (mitomycin C, interferon), or cryotherapy for squamous neoplasia 2
• Lymphoma requires systemic workup and oncology referral 1

Allergic/Inflammatory

• Topical antihistamines/mast cell stabilizers
• Topical corticosteroids for severe cases (short-term, monitor IOP)

Common Pitfalls to Avoid

1. Treating chronic unilateral conjunctivitis as "pink eye" without considering neoplasia - any lesion unresponsive after 4 weeks warrants biopsy 1
2. Missing gonococcal conjunctivitis - can rapidly progress to corneal perforation within 24-48 hours 1
3. Overlooking corneal involvement - always use fluorescein staining
4. Assuming all "bumps" are benign - sebaceous carcinoma, lymphoma, and melanoma can present subtly 1
5. Not obtaining cultures in suspected bacterial cases - especially important for chlamydial and gonococcal infections

When in doubt with any chronic, unresponsive, or atypical presentation, refer to ophthalmology for slit-lamp examination and possible biopsy.