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Phlyctenulosis

ROUTINE — Conjunctiva

Symptoms

  • tearing, irritation, and localized ocular pain
  • mild-to-severe photophobia (light sensitivity)
  • pediatric blepharospasm: a tearful child unable to open the eye
  • history of recurrent "styes" or chalazia
  • corneal lesions are significantly more painful than conjunctival ones

Clinical Findings

Characteristic lesion

  • the "phlycten": a small, raised, white-to-pink nodule at the limbus
  • intense focal wedge of dilated conjunctival vessels pointing toward the lesion
  • represent a type iv (delayed) hypersensitivity response

Corneal migration

  • "marching" phlyctenule: may migrate centrally across the cornea
  • leaves a "leash" of vessels and a wedge-shaped stromal scar behind it
  • can cause permanent vision loss if it crosses the visual axis

Associated lid disease

  • nearly always associated with staphylococcal blepharitis or mgd
  • ocular rosacea features (telangiectatic lid margins, recurrent chalazia)

Etiology

Pathophysiology

  • immune response to microbial antigens (staph, tb) deposited at the limbus
  • the nodule is sterile; it contains no live organisms

Primary triggers

  • staphylococcal antigens: the most common cause in developed nations
  • tuberculosis (tb): historically dominant; still critical in immigrants and children
  • others: hsv, chlamydia, candida, or intestinal parasites (ascaris/giardia)

Red Flags

  • central corneal migration: requires prompt steroids to prevent axial scarring
  • pediatric/immigrant cases: high suspicion for tuberculosis exposure
  • persistent lid disease: recurrent chalazia act as an antigenic reservoir
  • corneal melting: rare but suggests a severe inflammatory complication

Investigations

Slit lamp exam

  • evaluate lid margins for anterior blepharitis, collarettes, and mgd
  • document the position and any migration of the phlyctenule

Systemic screening (mandatory if recurrent/pediatric)

  • tb testing: ppd skin test and/or igra (quantiferon-tb gold)
  • chest x-ray: to rule out active or latent pulmonary tuberculosis

Specialized

  • stool ova & parasites: if parasites are suspected in a child from an endemic region

Treatment

For the phlyctenule

  • topical steroids: prednisolone acetate 1% or loteprednol 0.5% qid with a taper

For the lids

  • warm compresses and lid scrubs bid to reduce staph antigenic load
  • topical antibiotic ointment (erythromycin/bacitracin) to lid margins qhs

For rosacea/MGD

  • oral doxycycline (50–100mg bid) for 6–12 weeks; use erythromycin in children <8y

Systemic TB

  • if positive, refer to infectious disease for antituberculous therapy

Clinical Pearl

a phlyctenule in a child or immigrant patient is tuberculosis until proven otherwise — check ppd/igra before reaching for the topical steroid.

Differential Diagnosis

  • • inflamed pinguecula (usually horizontal/interpalpebral, lacks corneal migration)
  • • pterygium (fibrovascular growth, usually chronic and less inflammatory)
  • • marginal keratitis (staph infiltrates with a clear zone between lesion and limbus)
  • • ocular surface squamous neoplasia (ossn) (slower growth, abnormal vasculature)

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