Eye
Conjunctiva
Other nonneoplastic
Pterygium
Author: Pablo Zoroquiain, M.D.
Editor-in-Chief: Debra L. Zynger, M.D.
Topic Completed: 20 September 2019
Minor changes: 1 December 2020
Copyright: 2004-2019, PathologyOutlines.com, Inc.
PubMed Search: Pterygium conjunctiva [title]
Table of Contents
Definition / general | Essential features | ICD coding | Case reports | Epidemiology | Risk factors | Clinical features | Treatment | Clinical images | Gross description | Microscopic (histologic) description | Microscopic (histologic) images | Positive stains | Negative staining | Sample pathology report | Differential diagnosis | Board review style question #1 | Board review style answer #1 | Board review style question #2 | Board review style answer #2Cite this page: Zoroquiain P. Pterygium. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/eyepterygium.html. Accessed January 20th, 2021.
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
- 33 year old woman with growth in her eye (Am Fam Physician 2018;97:337)
- 40 year old man with mitomycin C excision and adjuvant extracellular matrix placement (Digit J Ophthalmol 2017;23:15)
- 60 year old man with corneal perforation associated with dellen after excision (BMJ Case Rep 2015 Nov 30;2015)
- 65 year old man with recurrent lesion treated with small incision lenticule extraction (J Int Med Res 2018;46:2474)
Epidemiology
- Prevalence of 12% with a geographic variation of 53% in China and 0.07% in Saudi Arabia (Surv Ophthalmol 2018;63:719)
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
- May cause squamous metaplasia with goblet cell loss
- Acanthosis or atrophy
- Conjunctival intraepithelial neoplasia primary acquired melanosis and nevus may coexist with pterygium (Saudi J Ophthalmol 2016;30:113, Histopathology 2006;48:387)
Microscopic (histologic) images
Contributed by Pablo Zoroquiain, M.D.
Elastotic degeneration
Corneo conjunctival junction
With cornea and conjunctiva
Elastotic infiltrate
Positive stains
- Abnormal expression of HSP90 and Ki67 (Diagn Pathol 2013;8:32)
- Stromal plaques: E-cadherin and beta catenin (Br J Ophthalmol 2007;91:1209)
Negative staining
- HSP90 negativity may be usefull to rule out ocular surface squamous neoplasia (Am J Clin Pathol 2016;145:385)
Sample pathology report
- Right eye, excision:
- Pterygium
Differential diagnosis
- Pinguecula: histologically similar but there is no corneal invasion clinically or pathologically
- Superior limbic keratoconjunctivitis: originates from the upper limbus
- Conjunctival intraepithelial neoplasia: epithelial dysplasia; can coexist and be overlooked
Board review style question #1
What finding in this sample is characteristic of pterygium?
- Bowman's layer fragmentation
- Elastosis of the lamina propria with corneal invasion
- Epithelial atrophy with goblet cell loss
- Neovascularization of the stroma
Board review style 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 style question #2
Which is the most important risk factor of pterygium?
- Chlamydia psittaci infection
- Human papilloma virus
- Sun exposure
- Tobacco and alcohol consumption
Board review style 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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Reference: Eye - Pterygium
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