• 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)

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

• 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)

Contributed by Pablo Zoroquiain, M.D.

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

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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Reference: Pterygium

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

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.

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Reference: Pterygium