Phlyctenular keratoconjunctivitis with viral triggers

Phlyctenular keratoconjunctivitis (PKC) goes beyond limbal nodules. This pediatric ocular surface condition caused by delayed-type hypersensitivity to microbial antigens. The trigger is context-dependent: Mycobacterial antigens in tuberculosis-endemic areas; staphylococcal eyelid disease and rosacea in high-income areas. Although classically bacterial-driven, virus-associated presentations like herpes simplex virus (HSV)-linked phlyctenular disease, pediatric PKC during acute coronavirus disease 2019 (COVID-19) infection, and molluscum contagiosum-driven keratoconjunctivitis suggest the same antigen-mediated pathway. Photophobia and discomfort are prevalent, and corneal involvement can cause neovascularization, scarring, amblyopia, and perforation. This minireview combines epidemiologic, clinical, and immunopathologic data to identify causes and update care. Practical takeaways: (1) Treat the antigen source (blepharitis/rosacea, chlamydia, parasites) and screen for tuberculosis when risk factors exist. Consider viral triggers when history or exam suggest HSV, recent COVID-19, or eyelid molluscum; (2) Suppress inflammation promptly with a short, carefully tapered course of topical corticosteroids; (3) Use topical cyclosporine as a steroid-sparing agent in recurrent or steroid-dependent disease; and (4) Reduce antigen load with lid hygiene and targeted antimicrobials. Start antitubercular treatment for tuberculosis. If a viral cause is anticipated, add antiviral medication or molluscum lesion eradication to the steroid-sparing regimen. Trigger-focused, steroid-sparing treatment reduces recurrences, vision-threatening consequences, and steroid exposure.