Differential Diagnosis for a Pimple on the Conjunctiva of the Eye

Single Most Likely Diagnosis

• Conjunctival papilloma: This is a benign growth on the conjunctiva, which could appear as a small pimple. It's relatively common and usually harmless.

Other Likely Diagnoses

• Conjunctivitis: Inflammation of the conjunctiva, which can cause small bumps or pimples, especially if caused by an allergic reaction or infection.
• Blepharitis: Inflammation of the eyelids that can lead to the formation of small pimples or bumps on the conjunctiva due to meibomian gland dysfunction.
• Chalazion: A small bump on the eyelid due to a blocked oil gland, which can sometimes appear on the conjunctival side of the eyelid.

Do Not Miss Diagnoses

• Basal cell carcinoma: Although rare, this type of skin cancer can appear on the conjunctiva and may initially resemble a pimple. Early detection is crucial for effective treatment.
• Squamous cell carcinoma: Another form of skin cancer that can occur on the conjunctiva, presenting as a pimple or a growth. It's less common but potentially more aggressive than basal cell carcinoma.
• Kaposi's sarcoma: In immunocompromised patients, this could present as lesions on the conjunctiva, among other places. It's a type of cancer that requires prompt medical attention.

Rare Diagnoses

• Conjunctival lymphoma: A rare cancer of the immune system that can manifest as a pimple or a mass on the conjunctiva.
• Conjunctival amyloidosis: A condition where abnormal proteins (amyloid) accumulate in the conjunctiva, potentially causing bumps or lesions that could be mistaken for pimples.
• Conjunctival cysts: Benign, fluid-filled sacs that can form on the conjunctiva, sometimes appearing as a pimple-like structure.