Eye
Conjunctiva: Benign
Pterygium

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

Topic Completed: 20 September 2019

Revised: 20 September 2019

Copyright: 2004-2019, PathologyOutlines.com, Inc.

PubMed Search: Pterygium conjunctiva [title]

Pablo Zoroquiain, M.D.
Page views in 2018: 6,944
Page views in 2019 to date: 11,022
Cite this page: Zoroquiain P. Pterygium. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/eyepterygium.html. Accessed December 13th, 2019.
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 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
Case reports
Epidemiology
Risk factors
  • Older age, M > F, rurality, outdoors activities, prolonged exposition to UV light and alcohol consumption (Surv Ophthalmol 2018;63:719)
Clinical features
  • Causes significant changes in corneal refractive status that increase 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 about 15% of the patients and it may masquerade as a neoplastic process
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 5FU): low recurrence, fast but can have complication secondary to the use of the adjunctive agents
    • Conjunctival flap or graft: is considered the gold standard with recurrence as low as 1/1,000 with autografts; it is a lengthier procedure and technically more difficult
Clinical images

Contributed by Dr. Arturo Grau M.D., M.Sc.

Corneo-limbal fleshy lesion

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

Corneo conjunctival junction

With cornea and conjunctiva

Elastotic infiltrate

Positive stains
Negative staining
Sample pathology report
  • Right eye, excision:
    • Pterygium
Differential diagnosis
Board review question #1
What finding in this sample is characteristic of pterygium?
  1. Bowman's 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 answer #1
B. Elastosis is the key morphological finding in pterygia. The infiltration of the corneal stroma is important 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's layer may be present but is also seen in keratoconus and other chronic keratitis.

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Board review question #2
Which is the most important risk factor of pterygium?

  1. Chlamydia psittaci infection
  2. Human papilloma virus
  3. Sun exposure
  4. Tobacco and alcohol consumption
Board review answer #2
C. Sun exposure is the most important risk factor. Human papilloma virus 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.

Reference: Eye - Pterygium

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