Uveal Nevi and Melanomas

Slide 1 · Uveal Nevi and Melanomas

Clinicopathologic foundations · molecular progression · prognosis

Dr Abu Suraih Sakhri

MBBS, MD (Pathology)

www.abusuraihsakhri.com

Slide 2 · Learning outcomes

1

Distinguish common uveal nevi from malignant uveal melanoma.

2

Explain GNAQ/GNA11 initiation and BAP1-associated progression.

3

Interpret morphology, dissemination and prognostic features.

4

Relate pathology to presentation and management.

Slide 3 · The uvea: Three connected tissues

Iris

Anterior uveal component; Melanoma limited to iris generally follows a less aggressive course.

Ciliary body

Intermediate uveal component; Tumors here belong to the more aggressive group.

Choroid

Posterior, highly vascularized uveal component; A frequent site for nevi and melanoma.

The vascular nature of the choroid is relevant to hematogenous dissemination.

Slide 4 · Anatomic context of a posterior uveal tumor

Pigmented posterior uveal lesion

Situated within the uveal wall.

May affect adjacent retina.

Schematic anatomy—not an observed specimen.

Slide 5 · Uveal nevi: Common benign melanocytic lesions

Uveal nevi are melanocytic lesions of the iris, ciliary body or choroid.

Choroidal nevi are particularly common.

Presence of a nevus does not, by itself, imply inevitable malignant transformation.

Benign lesions and melanoma may share early molecular alterations.

Slide 6 · Uveal melanoma: Why it matters

Most common PRIMARY intraocular malignancy in adults.

Biologically and genomically distinct from cutaneous melanoma.

Local control of the eye tumor does not abolish the risk of distant metastasis.

Primary intraocular malignancy ≠ most common intraocular malignancy overall.

Slide 7 · Primary melanoma versus ocular metastasis

Uveal melanoma

Primary adult intraocular cancer.

Originates within uveal tissues.

Characteristic molecular drivers.

Metastatic cancer to uvea

Most common intraocular adult malignancy overall.

Choroid is a frequent destination.

Classically from lung or breast.

Site of origin is the essential distinction.

Slide 8 · Epidemiologic scale of uveal melanoma

~5%

Approximate fraction of all melanomas represented by uveal melanoma in the United States.

5.1 / million / year

Age-adjusted U.S. Incidence reported in the Robbins source.

Adult malignancy

Predominant epidemiologic teaching context for primary intraocular melanoma.

Historical textbook estimates; Not a forecast of current population incidence.

Slide 9 · Uveal nevi are much more frequent than melanoma

~5%

Estimated uveal nevi prevalence among people of European descent, especially choroidal nevi.

Rare malignancy

Uveal melanoma incidence is reported per million persons per year.

Do not compare a prevalence proportion directly with an annual incidence rate.

Slide 10 · Incidence is relatively stable over time

Uveal melanoma

Textbook describes stable incidence across many years.

No clear UV–risk association established in this source.

Cutaneous melanoma

The epidemiologic pattern differs.

The underlying mutation spectrum also differs.

Do not extrapolate cutaneous melanoma trends to uveal melanoma.

Slide 11 · Ultraviolet exposure: Avoid assumed causality

The Robbins passage reports no clear link between UV exposure and uveal melanoma risk.

This epidemiologic pattern is consistent with a distinct oncogenic mechanism.

Absence of a clear population association is not proof that an exposure can never matter in an individual.

Slide 12 · Molecular contrast with cutaneous melanoma

Molecular feature

Uveal melanoma

Cutaneous melanoma

Canonical example

GNAQ / GNA11

BRAF (common driver)

BRAF in initiation

Not a principal driver

Frequent in subsets

Risk interpretation

Uveal-specific biology

Cannot be transferred directly

Textbook juxtaposition: Tumor site and mutation spectrum matter.

Slide 13 · GNAQ and GNA11 encode G-protein α subunits

GPCR at the cell membrane

Gαq / Gα11 signaling proteins

Growth-signaling pathways

Correction to source wording: These genes do NOT encode the receptors themselves.

Slide 14 · Activating mutations are frequent

Approximately 85% of uveal melanomas have activating GNAQ or GNA11 mutations in the source.

Both genes operate in a related G-protein signaling module.

Mutation prevalence alone does not indicate metastatic risk.

Frequent early driver ≠ sufficient explanation of malignant progression.

Slide 15 · How an activating G-protein mutation promotes growth

GNAQ or GNA11 gain-of-function

Persistent downstream signaling

MAPK-associated proliferative drive

Clonal expansion

Original pathway abstraction. Receptor coupling and multiple downstream branches are simplified.

Slide 16 · Uveal nevi can share the same initiating mutations

Benign nevus

May already contain GNAQ / GNA11 mutations.

Common and rarely progresses to melanoma.

Malignant melanoma

Often contains the same mutation class.

Additional genetic alterations are implicated.

A driver mutation must be interpreted in its biologic context.

Slide 17 · Why an early driver is not sufficient

Initiated melanocytic clone

Additional selected genetic changes

Loss of normal growth restraints

Malignant behavior

Multistep oncogenesis is an explanatory model, not a claimed obligatory timeline.

Slide 18 · Loss of chromosome 3 in progression

Loss of chromosome 3 is a consequential event in many uveal melanomas.

The deleted chromosome contains the tumor suppressor gene BAP1.

The selection for chromosome 3 loss can therefore remove tumor-suppressive functions.

Slide 19 · BAP1: A tumor-suppressive chromatin regulator

BAP1 encodes a deubiquitinating enzyme.

BAP1 participates in complexes involved in chromatin regulation.

Loss of BAP1 function can disrupt epigenetic control of gene expression.

GNAQ/GNA11 activation and BAP1 loss represent different biological roles.

Slide 20 · The epigenetic dimension of uveal melanoma

BAP1 dysfunction

Altered chromatin regulatory activity

Aberrant transcriptional programs

Tumor progression phenotype

Conceptual relationship; Exact loci, chromatin marks and targets are not specified.

Slide 21 · A two-stage molecular framework

Early signaling event

GNAQ / GNA11 activating mutation may be present in nevus or melanoma.

Additional progression event

Chromosome 3 loss and BAP1 dysfunction are implicated in malignant behavior.

Do not infer that every melanoma follows one fixed molecular sequence.

Slide 22 · BAP1 alterations can be inherited

Some patients carry a germline pathogenic BAP1 alteration.

A germline variant creates cancer predisposition; It does not establish that a given ocular lesion is malignant.

Tumor-only and constitutional variants are different interpretive categories.

Slide 23 · Germline BAP1: Associated tumor spectrum

Uveal melanoma

Ocular melanocytic malignancy

Renal cell carcinoma

Renal epithelial malignancy

Mesothelioma

Malignancy of mesothelial surfaces

The listed associations come from the textbook; No penetrance estimates are assumed.

Slide 24 · Initiating drivers versus progression alterations

Interpretive category

GNAQ / GNA11

Chromosome 3 / BAP1

Main role

Activation of growth pathways

Loss of suppressor / chromatin regulation

Presence in nevi

Possible

Not established by the excerpt

Clinical inference

Supports pathobiology

Associated with progression and risk

Mutation presence must not be equated with a complete diagnosis or prognosis.

Slide 25 · Histologic spectrum: Two classic cell patterns

Spindle cell type

Fusiform neoplastic cells.

Elongated cytomorphology.

Pure spindle tumors have more favorable prognosis relative to epithelioid-containing tumors.

Epithelioid cell type

Round to polygonal appearance.

Greater cytologic atypia.

An adverse morphologic prognostic feature.

Tumors may contain mixtures of both patterns.

Slide 26 · Spindle-cell morphology: Schematic

Fusiform profile

Elongated cells with tapered ends.

The spindle phenotype is one recognized uveal melanoma cell type.

Illustration is schematic—not a histologic specimen.

Slide 27 · Epithelioid morphology: Schematic

Greater cytologic atypia

Larger, more rounded cellular silhouette.

Epithelioid component is linked to worse prognosis.

Schematic, not a genuine H&E section.

Slide 28 · Mixed cellular composition is common

Spindle and epithelioid tumor cells can occur in varying proportions within one lesion.

Do not force a heterogeneous tumor into a purely spindle or purely epithelioid mental model.

The presence of an epithelioid component has prognostic implications.

Slide 29 · Tumor-infiltrating lymphocytes may be present

Some uveal melanomas display numerous infiltrating lymphocytes.

This histologic observation is also familiar in cutaneous melanoma.

The excerpt does not provide a validated prognostic direction or numeric cutoff for lymphocytes.

Recognition of an immune infiltrate is not equivalent to prognostic classification.

Slide 30 · Vasculogenic mimicry: The observed pattern

Some lesions show looping, slit-like channels around packets of tumor cells.

These spaces are lined by laminin and connect with blood vessels.

They are not conventional endothelial-lined blood vessels.

Slide 31 · Native schematic of laminin-lined tumor loops

Laminin-associated loop

Surrounds groups of melanoma cells

Schematic: NOT a blood vessel

Slide 32 · Vasculogenic mimicry is not ordinary angiogenesis

Ordinary vascular lumen

Endothelial vessel wall.

Blood transport through vessel lumen.

Vasculogenic mimicry

Tumor-associated laminin-lined spaces.

Connect to vessels; May conduct plasma or blood.

Do not label every loop as a capillary in a pathology diagram.

Slide 33 · Interpreting vasculogenic mimicry cautiously

In vitro studies and human tissues support tumor-cell participation in these growth patterns.

The textbook uses the term vasculogenic mimicry.

The precise functional contribution of each loop to perfusion cannot be inferred from morphology alone.

Slide 34 · Uveal melanoma disseminates hematogenously

Primary tumor in uvea

Entry into vascular circulation

Distant blood-borne deposits

Predilection for liver

Hematogenous spread is the rule; Classic lymph-node-first modeling is inappropriate.

Slide 35 · Liver tropism is a signature clinical feature

The liver is usually the first metastatic destination for uveal melanoma.

This is a classic example of organ-selective metastatic tropism.

Controlling the primary ocular lesion does not remove all risk of an occult disseminated clone.

Slide 36 · Rare exception: Access to conjunctival lymphatics

Scleral extension of melanoma

Invasion of conjunctiva

Access to conjunctival lymphatics

Lymphatic spread is exceptional in the source, not the dominant route.

Slide 37 · Why melanomas may be detected incidentally

Many uveal melanomas are discovered without tumor-specific symptoms.

A clinically quiet primary lesion can nevertheless carry metastatic potential.

Symptoms are therefore an unreliable surrogate for biologic aggressiveness.

Slide 38 · Retinal detachment links mass to symptoms

Choroidal tumor beneath retina

Disruption / elevation of overlying retina

Retinal detachment

Visual disturbance

Mechanism is a clinicopathologic interpretation of the source association.

Slide 39 · Glaucoma is another route to visual symptoms

Uveal mass or tumor-related effects

Interference with ocular aqueous dynamics

Raised intraocular pressure / glaucoma

Visual symptoms

The exact glaucoma mechanism varies by tumor location and is not specified by the excerpt.

Slide 40 · Primary site influences clinical behavior

Iris only

Often relatively indolent when confined to the iris.

Ciliary body

More aggressive behavior than lesions confined to iris.

Choroid

More aggressive behavior; Hematogenous metastatic risk.

Anatomic site modifies prognosis but does not replace other risk factors.

Slide 41 · Tumor dimensions: What matters in uveal melanoma

Larger choroidal and ciliary-body tumors have less favorable outcomes.

The source emphasizes lateral tumor extent in contrast to the depth emphasis familiar in cutaneous melanoma.

Anatomic measurements must be interpreted within the ocular staging framework, not by cutaneous melanoma rules.

Slide 42 · Cell type is prognostically informative

Spindle-only lesions

More favorable relative outcome in the classic morphologic comparison.

Fusiform tumor cell population.

Epithelioid-containing lesions

Worse relative prognosis.

Rounder, more atypical tumor cells.

Morphologic phenotype complements rather than replaces molecular risk assessment.

Slide 43 · Proliferative activity contributes to risk

The proliferative index is a prognostic factor in the Robbins account.

A higher index indicates greater tumor proliferative activity.

No numeric cutoff or required assay is specified in this source section.

Avoid inventing Ki-67 thresholds or grading algorithms.

Slide 44 · Gene expression profiling can stratify risk

Tumor gene expression pattern

Molecular risk categorization

Risk of future metastatic disease

The textbook supports prognostic stratification, not a claim that profiling predicts treatment response.

Slide 45 · Risk requires integration across domains

Morphologic

Tumor size, cell phenotype, proliferation.

Molecular

Expression-profile risk; Chromosome 3 / BAP1 biology.

Anatomic

Iris-confined versus ciliary-body / choroidal location.

These are complementary dimensions, not an arithmetic score.

Slide 46 · Long-term outcomes: Competing interpretations

Textbook endpoint

Estimate

Interpretation

Five-year survival

Approximately 80%

Survival to a defined time point

Ten-year cumulative melanoma mortality

About 40%

Disease-specific cumulative deaths

Late risk

Persists after treatment

Follow-up horizon matters

Do not equate five-year all-cause survival with ten-year melanoma-specific mortality.

Slide 47 · Late metastasis raises the problem of tumor dormancy

Treated ocular primary

Long interval without evident spread

Clinically detectable metastasis

Delayed detection does not prove when dissemination actually occurred.

Slide 48 · Primary ocular therapy: Preserve the eye when suitable

Eye-sparing radiotherapy

Textbook identifies radiotherapy as preferred local treatment.

Aims for local tumor control with ocular preservation.

Enucleation

Surgical removal of affected eye.

Retained for cases requiring removal.

Textbook reports no survival advantage for enucleation over radiotherapy.

Slide 49 · Local control and metastatic risk are different endpoints

Treat the ocular lesion

Achieve local tumor control

Continue assessment of systemic risk

A successful local procedure cannot guarantee prevention of late liver metastases.

Slide 50 · Updated metastatic treatment: Source correction

Textbook passage

States that no effective systemic treatment exists.

This statement is obsolete as current practice guidance.

Verified FDA update

Tebentafusp was approved in January 2022.

Indication is restricted to HLA-A*02:01-positive adults with unresectable or metastatic uveal melanoma.

External, separately verified update—not a claim about the printed Robbins wording.

Slide 51 · Tebentafusp requires an eligible HLA type

Unresectable / metastatic uveal melanoma

HLA-A*02:01 eligibility

Tebentafusp: T-cell redirection

Therapy is for a molecularly defined subset—not every patient with uveal melanoma.

Slide 52 · Nevus and melanoma: What this source supports

Feature

Uveal nevus

Uveal melanoma

Biology

Benign melanocytic lesion

Malignant melanocytic neoplasm

Frequency

Relatively common

Rare

GNAQ / GNA11

Can be mutated

Often mutated

Metastatic capacity

Not established

Characteristic systemic risk

This is conceptual comparison, not a validated clinical lesion-scoring system.

Slide 53 · Uveal versus cutaneous melanoma: Pitfalls

Domain

Uveal

Cutaneous

Principal drivers

GNAQ / GNA11

BRAF in a major subset

UV association

No clear association

Biology differs; Avoid extrapolation

Size concept

Lateral extent emphasized

Depth important in cutaneous staging

Spread

Usually hematogenous to liver

Different patterns

Different biologic diseases despite sharing melanocytic lineage.

Slide 54 · A pathology interpretation checklist

1

Confirm whether the lesion is intraocular and primary or metastatic.

2

Describe uveal site and morphology, including epithelioid component.

3

Characterize prognostic tumor dimensions and proliferation when available.

4

Interpret molecular findings by their diagnostic or prognostic role.

Slide 55 · Clinical reasoning case: A pigmented lesion

A choroidal pigmented lesion is found incidentally during routine examination.

Molecular testing identifies a GNAQ activating alteration.

Question: Does the mutation alone establish malignancy?

Apply the distinction between an initiating driver and malignant progression.

Slide 56 · Case interpretation: Mutation alone is insufficient

No: Benign uveal nevi can carry activating GNAQ / GNA11 mutations.

Malignancy requires interpretation of the complete clinical and pathologic context.

A driver mutation should not be converted into an unsupported binary diagnosis.

Slide 57 · Clinical reasoning case: Recurrence after years

A prior choroidal melanoma was treated locally years earlier.

A new liver mass is found after a long clinically disease-free interval.

Question: What dissemination mechanism and timing concept fit?

Slide 58 · Case interpretation: Hepatic tropism and dormancy

Uveal melanoma preferentially metastasizes to the liver via blood.

Late clinical metastasis is compatible with tumor dormancy.

A symptom-free interval does not prove absence of earlier dissemination.

Slide 59 · Synthesis: Molecular and clinical trajectory

Early GNAQ / GNA11 driver

Additional tumor-suppressor disruption

Uveal melanoma

Blood-borne liver metastasis

Conceptual sequence; Individual tumors vary and metastasis is not inevitable.

Slide 60 · Five conclusions to retain

Uveal melanoma is the commonest primary intraocular adult malignancy.

GNAQ / GNA11 are early G-protein drivers; BAP1 participates in progression.

Spindle and epithelioid cytomorphology informs prognosis.

Systemic dissemination is predominantly blood-borne, commonly to liver.

Therapy claims must distinguish the Robbins excerpt from current FDA approvals.

Slide 61 · References and source clarification

Robbins, Cotran & Kumar. Pathologic Basis of Disease. 11th ed. Chapter 29, p. 1197.

GNAQ/GNA11 protein identity: Cancers. 2022;14:3066. PMID: 35804836.

FDA: KIMMTRAK (tebentafusp) Drug Trials Snapshot; approval January 25, 2022.

External updates are distinguished from the extracted textbook prose.