Pterygium and Pinquecula

Slide 1 · Pterygium and pinguecula

Conjunctival actinic lesions

Pinguecula: conjunctival | Pterygium: corneal extension

Dr Abu Suraih Sakhri

MBBS, MD (Pathology)

www.abusuraihsakhri.com

Slide 2 · Learning outcomes

Locate the lesions in conjunctival anatomy and identify their UV-exposed distribution.

Distinguish a non-corneal pinguecula from a fibrovascular pterygium.

Explain stromal change, Bowman layer layer involvement, and refractive consequences.

Recognize red flags for ocular surface neoplasia and interpret excision specimens.

Slide 3 · A shared exposure; Two distinct growth patterns

Pinguecula

No corneal extension

Pterygium

Corneal fibrovascular advance

Schematic: Shared actinic exposure, different corneal relationships

Slide 4 · Conjunctival zones determine lesion location

Ocular surface zones (schematic cross-section)

Palpebral conjunctiva

Fornix

Bulbar conjunctiva

Limbus: Transition between bulbar conjunctiva and corneal epithelium. Pterygium is defined by advance beyond this boundary.

Slide 5 · The limbus is an anatomical and epithelial transition

The limbus joins bulbar conjunctiva to the cornea.

Conjunctival and corneal epithelia differ in their normal architecture.

Limbal stem-cell function helps maintain the corneal epithelial phenotype.

Conjunctival-to-corneal interface (schematic)

Conjunctiva

Cornea

Bowman-layer plane

Limbus separates conjunctival from corneal epithelium

Slide 6 · The interpalpebral fissure defines UV-exposed conjunctiva

Surface exposed between the upper and lower lids is the main site of these lesions.

Subepithelial elevations appear within this exposed band.

A lesion outside this expected distribution deserves careful reassessment.

Anterior ocular surface — schematic

Interpalpebral surface and corneal limbus

Slide 7 · Bulbar conjunctiva has a squamous epithelial covering

Normal bulbar conjunctiva is covered by nonkeratinizing stratified squamous epithelium.

The epithelium overlies a supportive subepithelial connective-tissue compartment.

Both lesions primarily remodel the subepithelial tissue, with variable epithelial response.

Simplified tissue section

Surface epithelium

Subepithelial conjunctival stroma

Deeper supporting tissue

Slide 8 · Actinic injury is the common etiologic theme

UV / environmental exposure

Chronic ocular surface injury

Localized stromal remodeling

Proposed etiologic sequence; Individual causal contributions vary

Slide 9 · Why the nasal limbus is commonly involved

Both disorders frequently involve the nasal interpalpebral conjunctiva.

Peripheral light focusing toward the nasal limbus is a proposed explanation.

Anatomical distribution supports — but does not independently prove — a single causal model.

Anterior ocular surface — schematic

Interpalpebral surface and corneal limbus

Slide 10 · Environmental association is not a quantitative risk model

Both lesions to actinic damage without specifying attributable fractions.

Evidence for the UV association is stronger for pterygium than some pinguecula associations.

Do not infer individual progression, recurrence, or cancer risk from appearance alone.

Slide 11 · Pinguecula: A limbal-adjacent conjunctival elevation

Typically a small, yellow-white, slightly raised lesion.

Located on interpalpebral bulbar conjunctiva close to the limbus.

Its defining feature is absence of corneal extension.

Anterior ocular surface — schematic

Conjunctival elevation; No corneal extension

Slide 12 · Pinguecula has a discrete, non-wedge geometry

The elevation is localized rather than a triangular advance across the cornea.

The conjunctiva remains the tissue of origin and the site of visible growth.

Color and elevation are descriptive — not histologic evidence by themselves.

Anterior ocular surface — schematic

Conjunctival elevation; No corneal extension

Slide 13 · The yellow-white appearance reflects stromal change

Subepithelial collagen shows degenerative, elastotic alteration.

Hyalinization may contribute to the gross appearance.

Do not assume that a yellow lesion is necessarily a primary lipid deposit.

Simplified tissue section

Surface epithelium

Subepithelial conjunctival stroma

Deeper supporting tissue

Slide 14 · Pinguecula: Stromal change beneath surface epithelium

Actinic-related stromal alteration lies below the epithelial surface.

Surface epithelium may be attenuated or reactive.

A conceptual cross-section explains localization; Diagnosis still depends on the real specimen.

Simplified tissue section

Surface epithelium

Subepithelial conjunctival stroma

Deeper supporting tissue

Elastotic / hyalinized stromal alteration

Slide 15 · Pinguecula is generally a benign surface finding

Most lesions are small and asymptomatic.

They are commonly encountered during routine ocular examination.

Presence alone does not establish visual dysfunction.

Slide 16 · Pingueculitis: Inflammation changes the presentation

Observation

Red, mildly elevated conjunctival patch

Process

Localized ocular-surface inflammation

Clinical impact

Irritation rather than corneal invasion

Slide 17 · Surface elevation can disturb the tear film

Raised conjunctival surface

Local tear-film instability

Irritation / inflammation

Local tear-film disturbance can explain irritation

Slide 18 · The cornea remains clear of pinguecular tissue

The lesion stops at or beside the limbus.

It does not form a fibrovascular head on the cornea.

Documenting this boundary is often sufficient for the primary clinical distinction.

Anterior ocular surface — schematic

Conjunctival elevation; No corneal extension

Slide 19 · Typical pinguecula is primarily a clinical diagnosis

1

Slit-lamp examination establishes color, contour, location, and corneal noninvolvement.

2

Clinical photographs may document size or change when useful.

3

Atypical pigmentation, growth, or epithelial features require a broader differential.

Slide 20 · Pinguecula: Management is usually conservative

Typical pinguecula?

YES

NO

Observe ± lubricants

Re-examine / refer

Slide 21 · Excision of pinguecula is selective, not routine

Symptoms, contact-lens interference, or substantial cosmetic concerns may prompt discussion.

Surgery itself can cause ocular surface disturbance and scarring.

When tissue is removed, examine it if diagnostic uncertainty exists.

Slide 22 · Pterygium: Fibrovascular growth onto the cornea

A wedge-shaped conjunctival growth crosses the limbus.

The advancing tissue carries stromal collagen and blood vessels.

The corneal extension — not merely conjunctival redness — defines the lesion.

Anterior ocular surface — schematic

Fibrovascular tissue advances onto the cornea

Slide 23 · A pterygium has a base, body, and advancing head

The body remains continuous with bulbar conjunctiva.

The head is the forward margin on the corneal surface.

The advanced edge can show a thin cap; These are clinical descriptors, not histologic tumor staging.

Base → body → advancing corneal head

Slide 24 · Pterygium tissue has a fibrovascular composition

Connective tissue matrix forms the bulk of the wedge.

Accompanying blood vessels account for its fleshy, vascular appearance.

The epithelium may show secondary reactive changes.

Simplified tissue section

Surface epithelium

Subepithelial conjunctival stroma

Deeper supporting tissue

Elastotic / hyalinized stromal alteration

Slide 25 · Pterygium remodels the Bowman-layer plane

Tissue dissecting into the plane normally occupied by Bowman layer.

Loss or disruption of Bowman layer may accompany fibrovascular ingrowth.

This corneal interface distinguishes pterygium from a purely conjunctival pinguecula.

Conjunctival-to-corneal interface (schematic)

Conjunctiva

Cornea

Bowman-layer plane

Fibrovascular tissue traverses the limbus

Slide 26 · Corneal extension requires tissue remodeling

Actinic injury / irritation

Fibrovascular remodeling

Extension across limbus

Remodeling is mechanistically plausible, not a molecular criterion

Slide 27 · Fibrovascularity explains the clinical appearance

Vessels track within the connective-tissue wedge.

A thicker, more vascular lesion may appear red and fleshy.

Color alone cannot reliably quantify its rate of progression.

Base → body → advancing corneal head

Slide 28 · A triangular lesion follows a corneal trajectory

The base is peripheral, typically on the nasal conjunctiva.

The apex advances toward the corneal center.

Progression should be documented by location and corneal extent, not assumed from one examination.

Anterior ocular surface — schematic

Fibrovascular tissue advances onto the cornea

Slide 29 · Pterygium may be quiet or inflamed

Dimension

Quiescent lesion

Inflamed lesion

Appearance

Thin or pale

Injected or fleshy

Discomfort

Often minimal

Burning / tearing

Next step

Document extent

Treat surface symptoms; Reassess

Slide 30 · Induced astigmatism is the principal refractive effect

Peripheral tissue can deform local corneal contour.

Progressive distortion may cause astigmatism and reduced visual quality.

Refractive impact may precede actual obscuration of the pupil.

Schematic curvature distortion ≠ measured topography

Slide 31 · Advanced lesions can impair the visual axis

Small lesions ordinarily spare the central optical axis.

Large or progressive lesions can approach or cover the visual axis.

This extends beyond Robbins’ brief description of typical limited visual threat.

Anterior ocular surface — schematic

Advanced growth may reach the central cornea

Slide 32 · Corneal distortion and central obstruction are different

Dimension

Astigmatism

Visual-axis involvement

Mechanism

Corneal shape alteration

Physical central encroachment

Early detection

Refraction / topography

Slit-lamp view / photograph

Consequence

Blur / irregular optics

Direct central vision compromise

Slide 33 · Primary and recurrent pterygia are distinct contexts

Dimension

Primary

Recurrent

History

No prior excision

Previous removal

Tissue planes

Often less scarred

Can be scarred or adherent

Planning

Initial risk assessment

Recurrence and surface reconstruction

Slide 34 · Clinical assessment begins with visual function

1

Measure visual acuity with appropriate correction.

2

Check refraction if vision complaints or suspected induced astigmatism exist.

3

Inspect corneal clarity and whether the lesion approaches the central optical zone.

Slide 35 · Describe the lesion reproducibly at the slit lamp

1

Record nasal or temporal location and extent onto the cornea.

2

Describe thickness, vascularity, inflammation, and mobility.

3

Look for focal leukoplakia, pigmentation, atypical vessels, or unusually rapid enlargement.

Slide 36 · Serial documentation identifies growth

Initial examination

Baseline extent documented

Repeat assessment for change

Use comparable documentation at each visit

Slide 37 · Corneal topography assesses refractive distortion

Topography can reveal localized or irregular corneal curvature change.

Use it when visual symptoms and lesion size appear discordant.

This is a functional evaluation; It is not a tissue diagnosis.

Schematic curvature distortion ≠ measured topography

Slide 38 · Anterior-segment OCT can aid selected differentials

Cross-sectional imaging can depict epithelial thickness and subepithelial tissue.

An unusually thick, hyperreflective epithelium raises concern for epithelial neoplasia.

OCT assists characterization but does not replace histopathology when indicated.

Epithelial layer

Subepithelial compartment

Layer mapping ≠ histologic diagnosis

Slide 39 · Pathology begins with a clinical question

Clinical impression

Excised conjunctival tissue

Stromal + epithelial review

Evaluate surface epithelium as well as stroma

Slide 40 · Histology: Actinic or elastotic stromal alteration

Degenerated, altered stromal collagen is a characteristic lesion substrate.

The finding is subepithelial and can accompany variable fibrosis and vascularity.

Histologic appearance should be interpreted in its anatomical context.

Simplified tissue section

Surface epithelium

Subepithelial conjunctival stroma

Deeper supporting tissue

Elastotic / hyalinized stromal alteration

Slide 41 · Histology: The pterygium epithelial compartment

Overlying conjunctival-type epithelium is often reactive.

Hyperplasia, keratinization, or dysplastic epithelial changes may be present.

Atypia should not be dismissed as part of ordinary actinic degeneration.

Simplified tissue section

Surface epithelium

Subepithelial conjunctival stroma

Deeper supporting tissue

Slide 42 · Histology: The advancing corneal interface

Fibrovascular tissue extends across the limbal boundary.

Disruption of Bowman layer supports the advancing corneal growth pattern.

Do not describe this benign stromal advance as malignant invasion.

Conjunctival-to-corneal interface (schematic)

Conjunctiva

Cornea

Bowman-layer plane

Fibrovascular tissue traverses the limbus

Slide 43 · Comparative pathology: One shared substrate, two locations

Dimension

Pinguecula

Pterygium

Gross contour

Focal yellow elevation

Wing-shaped fibrovascular wedge

Corneal involvement

Absent

Present

Stroma

Elastotic / hyalinized

Elastotic + fibrovascular

Bowman layer

No advancing interface

May be disrupted

Slide 44 · Benign pterygium and epithelial neoplasia may coexist

An actinic field can contain more than one pathologic process.

Some excised pterygia harbor dysplastic epithelial changes.

Therefore grossly innocuous appearance is not a guarantee of normal epithelium.

Slide 45 · Ocular surface squamous neoplasia is a crucial mimic

Dimension

Pterygium

Suspicious for OSSN

Surface

Usually smooth fibrovascular

May show leukoplakia / irregular plaque

Trajectory

Characteristic wing-shaped

Can be atypical / nodular

Diagnosis

Usually clinical

Targeted assessment ± tissue sampling

Slide 46 · Warning signs must override a reassuring label

Rapid change, irregular feeder vessels, pronounced leukoplakia, and atypical location warrant attention.

Unexpected pigmentation demands evaluation for melanocytic lesions.

A presumed pterygium should not conceal a limbal neoplasm.

Slide 47 · Melanocytic lesions belong in the limbal differential

Conjunctival nevus, melanocytic intraepithelial lesions, and melanoma can affect the ocular surface.

Pigmentation, unusual elevation, and acquired change alter the differential.

The distinction requires clinical examination; Some lesions require histopathology.

Slide 48 · Why pathology submission is worth considering

Excised pterygium

Histologic evaluation

Identify unexpected precursor

Incidental precursor lesions may alter interpretation

Slide 49 · Pseudopterygium may follow corneal surface injury

Dimension

True pterygium

Pseudopterygium

Setting

Actinic interpalpebral lesion

Prior injury / inflammation

Distribution

Usually nasal / temporal

May occur at atypical sites

Clinical action

Assess size and progression

Evaluate underlying corneal pathology

Slide 50 · Differential diagnosis uses site and tissue behavior

Dimension

Usual finding

Discriminating feature

Pinguecula

Raised yellow-white lesion

No corneal extension

Pterygium

Fibrovascular wedge

Extension across limbus

OSSN

Irregular epithelial plaque

Leukoplakia or atypical growth

Pseudopterygium

Adhesion after surface injury

Scarring or unusual location

Slide 51 · Case 1: Incidental yellow-white limbal elevation

Clinical vignette

A patient has a small nasal bulbar conjunctival elevation.

The corneal surface remains uninvolved; Vision is unaffected.

What single anatomical observation best supports pinguecula?

Slide 52 · Case 1: Anatomical boundary resolves the question

The defining observation is preserved corneal noninvolvement.

A focal raised yellow-white lesion next to the limbus supports pinguecula.

In an otherwise typical asymptomatic lesion, observation is appropriate.

Anterior ocular surface — schematic

Conjunctival elevation; No corneal extension

Slide 53 · Case 2: Blur with a nasal corneal wedge

Clinical vignette

A fibrovascular wedge extends from conjunctiva onto the nasal cornea.

The patient reports progressive blur despite a peripheral-looking lesion.

Which functional consequence should be assessed before any visual-axis obstruction?

Slide 54 · Case 2: Corneal shape explains the blurred vision

The lesion can distort corneal curvature before reaching the pupil.

Refraction and corneal topography help characterize the refractive effect.

Document progression and discuss referral if clinically significant.

Schematic curvature distortion ≠ measured topography

Slide 55 · Case 3: A presumed pterygium grows atypically

Clinical vignette

An irregular elevated limbal lesion develops leukoplakia and prominent vessels.

The change is faster than expected from earlier photographs.

Which diagnostic alternative must be considered?

Slide 56 · Case 3: Histology must exclude neoplasia

The lesion requires reassessment rather than labeling it uncomplicated pterygium.

OSSN is a high-priority epithelial differential.

If excised or biopsied, submit material for histopathology.

Slide 57 · Conservative care targets symptoms, not lesion removal

Minimal symptoms and stable?

YES

NO

Protection + lubrication + review

Assess visual impact / atypia

Slide 58 · Surgical referral depends on functional and diagnostic risk

Progression, impaired vision, or atypia?

YES

NO

Ophthalmic referral

Conservative follow-up

Slide 59 · Pterygium excision is not biologically trivial

Excision

Ocular surface repair

Monitor healing / regrowth

Recurrence is a recognized wound-healing complication

Slide 60 · Follow-up must assess recurrence and ocular surface health

1

Examine the surgical site for recurrent fibrovascular extension.

2

Assess corneal surface, scar, inflammation, and refractive change.

3

Maintain UV protection; Do not infer a zero-recurrence guarantee.

Slide 61 · Prevention emphasizes ocular UV protection

Limit cumulative UV

Reduce surface irritation

Monitor established lesions

Protection limits exposure but does not remove an existing lesion

Slide 62 · Diagnostic comparison: Three questions decide much

1

Does the lesion enter the cornea?

2

Is its architecture a characteristic fibrovascular wedge?

3

Are there atypical epithelial or melanocytic features?

Slide 63 · Clinicopathologic synthesis

Shared exposure: Chronic actinic ocular surface injury.

Pinguecula: Conjunctival, yellow-white, non-corneal stromal degeneration.

Pterygium: Fibrovascular growth onto cornea, with Bowman-layer involvement.

Atypical lesions and removed tissue deserve assessment for neoplastic precursors.

Slide 64 · References and source scope

Robbins, Cotran & Kumar: Pathologic Basis of Disease, 11th edition, Chapter 29.

National Eye Institute: ultraviolet exposure and ocular surface lesions.

NCBI Bookshelf/StatPearls: pterygium clinical assessment and management.

Austin and colleagues: elastotic changes in pterygium and pinguecula (Ophthalmology, 1983).