Eye

Conjunctiva

Other nonneoplastic

Pterygium


Editor-in-Chief: Debra L. Zynger, M.D.
Pablo Zoroquiain, M.D.

Last author update: 5 December 2022
Last staff update: 5 December 2022 (update in progress)

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PubMed Search: Pterygium conjunctiva

Pablo Zoroquiain, M.D.
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Cite this page: Zoroquiain P. Pterygium. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/eyepterygium.html. Accessed December 6th, 2022.
Definition / general
  • Frequent, degenerative ocular surface lesion, characterized by invasion of the cornea by a fibrovascular tissue originating from the bulbar conjunctiva (Surv Ophthalmol 2018;63:719)
  • Most frequent in the interpalpebral area, nasal side
  • Thought to be UV light associated; not associated with human papillomavirus (HPV) (Br J Ophthalmol 200;91:1016)
  • Develops from limbal epithelial progenitors; may be a stem cell disorder with possible premalignant features (Am J Pathol 2011;178:817)
Essential features
  • Frequent, degenerative ocular surface lesion
  • Similar to pinguecula but with corneal infiltration
  • UV related
  • Can masquerade as a neoplastic process
  • Fibrovascular connective tissue that migrates to cornea
ICD coding
  • ICD-10: H11.0 - pterygium of eye
Epidemiology
Sites
  • Corneoconjunctival limbus and cornea
Pathophysiology
  • There are many hypotheses but its pathogenesis is still unknown
  • Environmental factors have been suggested, due to high prevalence in hot and dry climates
  • UV radiation has been proposed, due to the similarity with the histopathology of solar elastosis
  • Other proposed hypotheses are corneal stem cell deficiency, inflammation, angiogenic disregulation, ultraviolet albedo (reflected, scattered light) in the anterior eye (Br J Ophthalmol 1993;77:734)
Etiology
  • Older age, M > F, rurality, outdoor activities, prolonged exposure to UV light and alcohol consumption are known risk factors (Surv Ophthalmol 2018;63:719)
Clinical features
  • Causes significant changes in corneal refractive status that increases with grade of pterygia (Indian J Ophthalmol 2007;55:383)
  • High prevalence (18%) in those older than 40 living at high altitude in Mongolia (Eye (Lond) 2009;23:421)
  • Clinically, may resemble ocular surface squamous neoplasia or melanoma
  • Not related to multiple pterygium (webbing) syndrome (Am J Hum Genet 2006;79:390)
  • Recurs in ~15% of patients and may masquerade as a neoplastic process
Diagnosis
  • Diagnosis is performed when the typical clinical appearance is observed
Prognostic factors
  • Recurrence rate is lower than 1/1,000 surgical procedures
Case reports
Treatment
  • Treatment for cosmetic reasons, visual impairment, recurrent inflammation, mild irritation
  • Medical therapy:
    • Symptoms can be alleviated using over the counter vasoconstrictor drops and lubricating agents such as ointments or drops
    • Corneal extension should be followed to determine the growth ratio to the visual axis
  • Surgery:
    • Excision with adjunctive therapies (radiotherapy, mitomycin C or fluorouracil [5FU]): low recurrence and fast but can have complication secondary to the use of the adjunctive agents
    • Conjunctival flap or graft: considered the gold standard with recurrence as low as 1/1,000 with autografts; it is a lengthier procedure and technically more difficult
  • References: Ther Adv Ophthalmol 2021;13:25158414211020152, J Curr Ophthalmol 2022;33:367
Clinical images

Contributed by Arturo Grau, M.D., M.Sc.
Corneolimbal fleshy lesion

Corneolimbal fleshy lesion

Fibrovascular pattern

Fibrovascular pattern

Gross description
  • Fleshy
  • Grossing tip: always bisect the tissue from the conjunctiva to the cornea
Microscopic (histologic) description
  • Stromal changes:
    • Fibrovascular connective tissue that migrates from the conjunctiva to cornea, dissecting into plane of Bowman layer, leading to fragmentation
    • Fibrovascular core is composed of collagen mixed with basophilic fibrillar structures and blood vessels, all in variable amounts
    • Variable acute and chronic inflammatory infiltrate
  • Epithelial changes:
Microscopic (histologic) images

Contributed by Pablo Zoroquiain, M.D.
Elastotic degeneration

Elastotic degeneration

Corneoconjunctival junction

Corneoconjunctival
junction

With cornea and conjunctiva

With cornea and conjunctiva

Elastotic infiltrate

Elastotic infiltrate

Positive stains
Negative stains
Sample pathology report
  • Right eye, excision:
    • Pterygium
Differential diagnosis
Board review style question #1

Which finding in the sample seen above is characteristic of pterygium?

  1. Bowman layer fragmentation
  2. Elastosis of the lamina propria with corneal invasion
  3. Epithelial atrophy with goblet cell loss
  4. Neovascularization of the stroma
Board review style answer #1
B. Elastosis of the lamina propria with corneal invasion. Elastosis is the key morphological finding in pterygia. The infiltration of the corneal stroma is important to be able to differentiate it from a pinguecula when there is no clinical information. Epithelial atrophy with goblet cell loss is nonspecific and can be seen in dry eye syndrome or superior limbic keratoconjunctivitis. Neovascularization is present in most of pterygia but is also seen in many other conjunctival inflammatory processes. Fragmentation of the Bowman layer may be present but is also seen in keratoconus and other chronic keratitis.

Comment Here

Reference: Pterygium
Board review style question #2
Which of the following is the most important risk factor of pterygium?

  1. Chlamydia psittaci infection
  2. Human papillomavirus
  3. Sun exposure
  4. Tobacco and alcohol consumption
Board review style answer #2
C. Sun exposure is the most important risk factor. Human papillomavirus is not strongly associated with either pterygium or conjunctival intraepithelial neoplasia. Chlamydia psittaci has been associated with some MALT lymphomas but has not been associated with pterygium. Alcohol and tobacco have been listed as possible predisposing factors but are not as prevalent as sun exposure.

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Reference: Pterygium
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