Differential Diagnosis for a Sore in the Outer Corner of the Eye
Single Most Likely Diagnosis
- Blepharitis or Hordeolum (Stye): The description of a sore in the outer corner of the eye that is draining and shiny to touch, accompanied by a burning sensation, is highly suggestive of an external eye infection such as blepharitis or a hordeolum (stye). These conditions are common and typically present with localized inflammation, discharge, and discomfort.
Other Likely Diagnoses
- Conjunctivitis: This could be either viral or bacterial, presenting with discharge and irritation. The location in the outer corner could be indicative of a conjunctival issue rather than a skin or eyelid margin problem.
- Keratitis: An inflammation of the cornea that could cause pain, burning, and possibly discharge, especially if there's an associated infection.
- Dacryocystitis: An infection of the lacrimal sac, which could cause pain, swelling, and discharge in the medial (inner) corner of the eye but could potentially affect the outer corner if the infection spreads or if there's an anatomical abnormality.
Do Not Miss Diagnoses
- Orbital Cellulitis: Although less likely given the localized nature of the symptoms, orbital cellulitis is a serious infection that requires prompt treatment to prevent complications such as vision loss or intracranial spread. It typically presents with more severe symptoms including significant swelling, proptosis, and possibly fever.
- Malignancy (e.g., Basal Cell Carcinoma or Squamous Cell Carcinoma): While rare, a persistent sore or lesion in the eye area could be a sign of skin cancer. Given the potential for serious consequences if missed, it's crucial to consider and rule out malignancy, especially in individuals with risk factors.
Rare Diagnoses
- Actinic Keratosis: A precursor to squamous cell carcinoma, it could present as a persistent sore but is less likely to be in the corner of the eye and more commonly found on sun-exposed areas.
- Gout or Pseudogout of the Eye: Deposits of uric acid or calcium pyrophosphate dihydrate crystals around the eye can cause inflammation and mimic an infectious process, though this would be an unusual presentation.
- Sjögren's Syndrome: An autoimmune disorder that can cause dry eyes and potentially lead to secondary infections or corneal ulcers, presenting with a sore or burning sensation in the eyes.