Differential Diagnosis for a Painful Stye on the Lower Right Eyelid
- Single Most Likely Diagnosis
- Hordeolum (Stye): This is the most likely diagnosis given the patient's symptoms of a painful stye on the lower right eyelid with thick yellow pus discharge. A hordeolum is an acute, localized infection or inflammation of the eyelid margin involving hair follicles of the eyelashes (external hordeolum) or meibomian glands (internal hordeolum).
- Other Likely Diagnoses
- Chalazion: Although typically less painful and more chronic than a hordeolum, a chalazion (a blocked oil gland in the eyelid) can sometimes present with significant discomfort and discharge if it becomes infected. The absence of systemic symptoms and vision changes makes this less likely but still a consideration.
- Blepharitis: This is an inflammation of the eyelids that can cause redness, itching, and swelling. While it might not directly cause a stye, it can predispose to hordeolum formation and could be a contributing factor to the patient's discomfort.
- Do Not Miss Diagnoses
- Orbital Cellulitis: Although the patient reports no systemic symptoms or vision changes, orbital cellulitis is a serious infection of the tissues surrounding the eye that can present with eyelid swelling, redness, and discharge. It requires prompt medical attention to prevent serious complications, including vision loss.
- Preseptal Cellulitis: Similar to orbital cellulitis but less severe, preseptal cellulitis involves infection of the eyelid and tissues anterior to the orbital septum. It can present with significant swelling, redness, and sometimes discharge, and while less dangerous than orbital cellulitis, it still requires medical evaluation.
- Rare Diagnoses
- Dacryocystitis: An infection of the lacrimal sac, which can cause pain, redness, and swelling of the eyelid, particularly in the area of the medial canthus. It's less common and usually associated with nasolacrimal duct obstruction.
- Methicillin-Resistant Staphylococcus aureus (MRSA) Infection: Although less common, MRSA can cause skin and soft tissue infections, including those of the eyelid. The presence of thick yellow pus discharge could suggest a bacterial infection, and MRSA should be considered, especially if the patient does not respond to standard antibiotic treatments.