Phlyctenular keratoconjunctivitis is a delayed hypersensitivity response to microbial antigens. In modern urban practice, the most common inciting antigen is derived from:

• A Mycobacterium tuberculosis
• B Adenovirus capsid antigens
• C Ascaris lumbricoides
• D Staphylococcus aureus cell wall proteins ✓

Explanation

A phlycten is a focal non-suppurative nodular lesion of the limbal or bulbar conjunctiva representing a type IV delayed hypersensitivity reaction. Historically tuberculosis was the dominant antigen, but today staphylococcal antigens associated with chronic blepharitis are the most frequent cause in developed and urban settings. Ascaris and other parasitic antigens are rare causes, and adenovirus is not linked to phlyctenulosis.

Reference: Parsons' Diseases of the Eye, 23rd ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.