Cystic Neoplasms

Slide 1 · Cystic Neoplasms

Pancreatic pathology

Morphology · molecular profiles · malignant potential

Dr Abu Suraih Sakhri

MBBS, MD (Pathology)

www.abusuraihsakhri.com

Slide 2 · Learning objectives

Discriminate nonneoplastic cysts from pancreatic cystic neoplasms.

Recognize defining morphology and anatomical patterns of four major neoplastic groups.

Relate recurrent mutations to diagnostic differentiation and malignant potential.

Explain when a noninvasive mucinous lesion becomes clinically important.

Slide 3 · Pancreatic cysts form a biologically mixed group

Pancreatic cyst

Nonneoplastic process

Cystic neoplasm

Variable malignant potential

Conceptual pathway; Arrows denote stated biological or clinical relationships.

Slide 4 · Only a minority of pancreatic cysts are neoplastic

5%–15%

Of pancreatic cysts are neoplastic

<5%

Of pancreatic neoplasms are cystic

Slide 5 · Four major pancreatic cystic neoplasms

Serous cystic neoplasm

Microcysts · clear fluid · VHL

Mucinous cystic neoplasm

Mucin + ovarian stroma · KRAS / RNF43

Intraductal papillary mucinous neoplasm

Duct-centered mucin · GNAS

Solid pseudopapillary neoplasm

Solid–cystic · hemorrhage · CTNNB1

Slide 6 · A pancreatic pseudocyst is not a cystic neoplasm

Pseudocysts result from walled-off hemorrhagic fat necrosis.

The wall contains fibrosis and granulation tissue, not a true epithelial lining.

An epithelial-lined neoplasm must not be confused with a pseudocyst.

Granulation / fibrous wall

NO epithelial lining

Schematic · not a clinical or histologic specimen

Slide 7 · Congenital cysts provide a second comparator

Congenital pancreatic cysts can be lined by cuboidal or attenuated epithelium.

They are typically thin-walled and contain clear serous fluid.

A true epithelial lining does not by itself imply a neoplasm.

Thin epithelial lining

Schematic · not a clinical or histologic specimen

Slide 8 · Four observations guide morphological classification

Entity

Architecture

Cyst contents

Key tissue clue

SCN

Microcysts

Clear fluid

Glycogen-rich cells

MCN

Large cysts

Thick mucin

Ovarian-type stroma

IPMN

Dilated ducts

Mucin

Main / branch ducts

SPN

Solid + cystic

Hemorrhagic

Pseudopapillae

Slide 9 · Serous cystic neoplasms are nearly always benign

Serous cystic neoplasm

Microcystic lesion

Virtually benign

Resection usually curative

Conceptual pathway; Arrows denote stated biological or clinical relationships.

Slide 10 · SCN: Demographic distribution

Serous lesions represent 15%–25% of all pancreatic cystic neoplasms.

They occur about twice as often in females as in males.

Typical clinical presentation is in the sixth to seventh decades.

15%–25%

Of pancreatic cystic neoplasms

Slide 11 · SCN: Characteristic pancreatic location

SCNs usually occur in the pancreatic tail.

Location is supportive rather than independently diagnostic.

Demographics, imaging architecture and epithelial phenotype must be integrated.

HEAD

BODY

TAIL

Conceptual head–body–tail orientation (not anatomical scale)

Slide 12 · SCN: Microcystic honeycomb architecture

Individual cysts are usually small: Approximately 1–3 mm.

Cysts may be solitary, multiple or arranged as a honeycomb of microcysts.

The small-cyst pattern contrasts with the larger cavities of MCN.

Small, crowded cavities

Schematic · not a clinical or histologic specimen

Slide 13 · SCN: Glycogen-rich epithelial cells

Serous cavities are lined by cuboidal epithelium.

The neoplastic lining cells contain abundant glycogen.

The cited illustration describes bland cuboidal cells without atypia.

Cuboidal, glycogen-rich cells

Schematic · not a clinical or histologic specimen

Slide 14 · SCN: Clear, watery cyst contents

Serous cysts contain thin, clear, straw-colored fluid.

Fluid appearance accords with the non-mucinous epithelial phenotype.

Compare with MCN: Thick and tenacious mucin is the key alternative.

SCN

Clear, thin, straw-colored fluid

MCN

Thick, tenacious mucin

Slide 15 · SCN: VHL inactivation is the characteristic alteration

Inactivation of the VHL tumor suppressor gene is most common.

The VHL locus is on chromosome 3p.

This profile contrasts with KRAS-, RNF43- and GNAS-associated mucinous lesions.

VHL

Most common SCN genetic abnormality

Slide 16 · SCN: Incidental discovery is common

Many serous lesions are found on imaging performed for another reason.

Others cause nonspecific abdominal pain.

Symptoms alone do not differentiate benign SCN from a precursor lesion.

Slide 17 · SCN: Clinicopathologic synthesis

Typical pattern: Older patient, tail-based microcystic lesion and clear fluid.

Bland glycogen-rich cuboidal lining reinforces the diagnosis.

A VHL-centered molecular profile is distinct from the mucinous neoplasms.

Small, crowded cavities

Schematic · not a clinical or histologic specimen

Slide 18 · MCN is a genuine precursor to invasive carcinoma

Mucinous cystic neoplasm

Noninvasive precursor

Possible invasion

Potentially lethal carcinoma

Conceptual pathway; Arrows denote stated biological or clinical relationships.

Slide 19 · MCN has a marked female predominance

Nearly 95% of MCNs arise in females.

This striking distribution contrasts with IPMN, which is more frequent in males.

Sex is supportive clinical evidence, not a histologic diagnostic criterion.

≈95%

Of MCNs arise in females

Slide 20 · MCN commonly arises in the pancreatic tail

Most MCNs arise in the tail of the pancreas.

The same broad location is common for SCN: Additional features must distinguish them.

IPMN, by contrast, tends to involve the pancreatic head.

HEAD

BODY

TAIL

Conceptual head–body–tail orientation (not anatomical scale)

Slide 21 · MCN commonly presents as a slow-growing mass

Mucinous lesions may present as painless, slow-growing pancreatic masses.

Absence of pain does not establish innocuous biology.

Gross and microscopic architecture determine the distinctive diagnosis.

Slide 22 · MCN: Larger cystic cavities

MCN cavities are generally larger than serous microcysts.

The lesion may be multiloculated and arises commonly in the pancreatic tail.

A large-cyst appearance supports, but does not independently prove, MCN.

Large mucin-filled cavities

Schematic · not a clinical or histologic specimen

Slide 23 · MCN: Viscous luminal mucin

The cavities are filled with thick, tenacious mucin.

The content reflects a mucin-producing epithelial lining.

Macroscopic fluid character helps distinguish mucinous from serous patterns.

Serous contents

Watery / straw-colored

Mucinous contents

Viscous / tenacious

Slide 24 · MCN: Columnar mucin-producing epithelium

A columnar mucinous epithelial lining is a defining morphological component.

The lining must be interpreted with the underlying stromal phenotype.

Invasive carcinoma, if present, changes biological classification and prognosis.

Mucin-rich lumen

Columnar lining (inner border)

Ovarian-type stroma (outer band)

Schematic · not a clinical or histologic specimen

Slide 25 · MCN: Ovarian-type stroma is a decisive feature

Dense stroma resembling ovarian stroma supports MCN.

The combination of mucinous lining and ovarian-type stroma distinguishes MCN from IPMN.

IPMN lacks the dense ovarian-type stroma of MCN.

Mucin-rich lumen

Columnar lining (inner border)

Ovarian-type stroma (outer band)

Schematic · not a clinical or histologic specimen

Slide 26 · MCN: Stromal immunophenotype

Marker

Compartment

Interpretive role

Estrogen receptor

Ovarian-type stroma

Supports stromal phenotype

Progesterone receptor

Ovarian-type stroma

Supports stromal phenotype

Inhibin

Ovarian-type stroma

Supports stromal phenotype

Slide 27 · MCN: Integrate two essential tissue components

Mucin-producing columnar epithelium forms the cyst lining.

Dense ovarian-type stroma forms the characteristic supporting tissue.

Neither pancreatic tail location nor mucin alone substitutes for the composite morphology.

Mucin-rich lumen

Columnar lining (inner border)

Ovarian-type stroma (outer band)

Schematic · not a clinical or histologic specimen

Slide 28 · MCN: Invasion can already be present at detection

Up to one-third of MCNs harbor an invasive adenocarcinoma.

A neoplasm containing invasion is distinct from a noninvasive precursor.

This is why assessment for invasive growth is central to specimen evaluation.

Up to ⅓

May harbor invasive adenocarcinoma

Slide 29 · MCN: Prognosis changes with invasive carcinoma

Noninvasive

Resection is curative

Up to 50%

5-year mortality with invasive cancer

Slide 30 · MCN: KRAS is a common early-profile alteration

Oncogenic KRAS mutations occur in approximately half of MCNs.

KRAS is part of the MCN-associated molecular profile.

KRAS alteration alone is not specific enough to replace morphology.

KRAS

Mutated in approximately half of MCNs

Slide 31 · MCN: RNF43 loss is another recurrent alteration

RNF43

Normally downregulates Wnt signaling

Loss of function

Reduced pathway restraint

Conceptual pathway; Arrows denote stated biological or clinical relationships.

Slide 32 · MCN: TP53 and SMAD4 accompany invasive disease

TP53 and SMAD4 mutations are typically seen in invasive neoplasms arising from MCN.

Their association with invasion differs from frequent KRAS mutations in MCNs.

The source supports this association; It does not provide a deterministic gene sequence.

TP53 · SMAD4

Typically associated with invasive MCN-derived carcinoma

Slide 33 · MCN: The clinical turning point is invasion

Mucinous epithelium + ovarian stroma

Noninvasive neoplasm

Invasive carcinoma possible

Prognosis changes

Conceptual pathway; Arrows denote stated biological or clinical relationships.

Slide 34 · IPMN is an intraductal mucin-producing neoplasm

Intraductal papillary mucinous neoplasms involve the larger pancreatic ducts.

Their relationship to main or branch ducts is a defining anatomical feature.

This duct-centered pattern distinguishes them from MCN.

Main pancreatic duct

Branch ducts

Intraductal projections

Schematic · not a clinical or histologic specimen

Slide 35 · IPMN can involve main or branch pancreatic ducts

IPMN arises in the main pancreatic duct or one of its branch ducts.

Duct dilatation and intraductal epithelial growth form the conceptual architecture.

Mucinous character alone cannot distinguish IPMN from MCN.

Main pancreatic duct

Branch ducts

Intraductal projections

Schematic · not a clinical or histologic specimen

Slide 36 · IPMN differs from MCN in sex and regional bias

IPMNs arise more frequently in males.

They tend to involve the pancreatic head.

MCNs, by contrast, predominantly affect females and the pancreatic tail.

IPMN

More common in males · head preference

MCN

~95% female · tail preference

Slide 37 · IPMN can be multifocal

Up to 20% of IPMNs are multifocal.

The possibility of multiple lesions reflects their intraductal disease pattern.

The source does not specify a required imaging or surgical surveillance protocol.

Up to 20%

IPMNs may be multifocal

Slide 38 · IPMN lacks MCN-type ovarian stroma

The absence of dense ovarian-type stroma is diagnostically useful.

The other major discriminator is involvement of the pancreatic duct system.

Both features should be evaluated together; Location and sex are supporting clues.

MCN

Mucinous lining + ovarian-type stroma

IPMN

Mucinous epithelium + duct involvement

Slide 39 · IPMN: Progression to invasion is the main hazard

Intraductal mucinous neoplasm

Noninvasive IPMN

Potential invasion

Invasive carcinoma

Conceptual pathway; Arrows denote stated biological or clinical relationships.

Slide 40 · IPMN: KRAS alterations are frequent

Oncogenic KRAS mutations occur in approximately 80% of IPMNs.

This is more frequent than the approximately half of MCNs cited in the text.

Shared KRAS mutations do not erase distinctive tissue architecture.

KRAS

Mutated in approximately 80% of IPMNs

Slide 41 · IPMN: RNF43 loss recurs

Loss-of-function RNF43 mutations occur in up to 50% of IPMNs.

These alterations also occur in MCNs.

RNF43 is therefore shared across mucinous neoplasms, not specific to IPMN.

RNF43

Loss-of-function in up to 50% of IPMNs

Slide 42 · IPMN: BRAF alterations form an additional subset

BRAF alterations occur in approximately 10% of IPMNs.

Their reported presence broadens the IPMN molecular spectrum.

This figure is a source-reported frequency, not a diagnostic threshold.

BRAF

Altered in approximately 10% of IPMNs

Slide 43 · IPMN: GNAS is a major discriminating signature

Oncogenic GNAS mutations occur in approximately two-thirds of IPMNs.

GNAS encodes the α subunit of the stimulatory G protein (Gαs).

The Robbins excerpt states these mutations are not found in other pancreatic cysts.

GNAS

Approximately two-thirds of IPMNs; Distinguished in source

Slide 44 · IPMN: TP53 and SMAD4 are invasion-associated

TP53 and SMAD4 mutations typically occur with transition to invasive cancer.

This is analogous to the invasion-associated pattern described for MCN.

The mutation association should not be presented as a complete staging system.

TP53 · SMAD4

Typically associated with invasive transition

Slide 45 · IPMN: Shared versus distinguishing alterations

Alteration

MCN

IPMN

KRAS

≈50%

≈80%

RNF43

Up to ⅓

Up to 50%

GNAS

Not reported as typical

≈⅔; Highlighted as distinctive

TP53 / SMAD4

Usually with invasion

Usually with invasion

Slide 46 · SPN is a distinctive, uncommon pancreatic tumor

Solid pseudopapillary neoplasms are uncommon.

They differ from secretory cystic neoplasms because both solid and cystic components are typical.

The diagnosis integrates characteristic architecture and a distinct CTNNB1 profile.

Solid areas + hemorrhagic cyst

Schematic · not a clinical or histologic specimen

Slide 47 · SPN mainly affects young females

Solid pseudopapillary neoplasms occur primarily in young females.

Lesions often become large before presentation.

Abdominal discomfort may reflect their size.

Slide 48 · SPN: Mixed solid and cystic cut surface

The tumor is usually well circumscribed.

Solid components coexist with cystic spaces.

The cystic portions contain hemorrhagic debris, not characteristic serous fluid or mucin.

Solid areas + hemorrhagic cyst

Schematic · not a clinical or histologic specimen

Slide 49 · SPN: Pseudopapillary growth pattern

Tumor cells may form solid sheets or pseudopapillary projections.

The neoplastic cells often appear poorly cohesive.

These architectural features explain the term “solid pseudopapillary.”

Solid sheets / pseudopapillae

Schematic · not a clinical or histologic specimen

Slide 50 · SPN: Nearly universal CTNNB1 activation

Activating CTNNB1 (β-catenin) mutations occur in nearly all SPNs.

The predominance of CTNNB1 is a key molecular contrast with SCN, MCN and IPMN.

The excerpt does not prescribe a separate molecular testing algorithm.

CTNNB1

Activating mutations in nearly all SPNs

Slide 51 · SPN: Other cystic-tumor driver profiles are absent

SPN profile

Mutation pattern

CTNNB1 (β-catenin)

Activating mutations: Nearly all

KRAS / RNF43

Not observed in source description

GNAS / VHL

Not observed in source description

Slide 52 · SPN: Resection is usually curative

SPN recognition

Well-circumscribed tumor

Surgical resection

Curative in most

Conceptual pathway; Arrows denote stated biological or clinical relationships.

Slide 53 · Four entities: Structural signatures

Serous cystic neoplasm

Microcysts · clear fluid · VHL

Mucinous cystic neoplasm

Mucin + ovarian stroma · KRAS / RNF43

Intraductal papillary mucinous neoplasm

Duct-centered mucin · GNAS

Solid pseudopapillary neoplasm

Solid–cystic · hemorrhage · CTNNB1

Slide 54 · Morphology is the anchor of differentiation

Neoplasm

Architecture

Contents / cell clue

SCN

Microcystic

Clear fluid; Glycogen-rich cuboidal lining

MCN

Large cysts

Mucin; Ovarian-type stroma

IPMN

Duct-centered

Mucin-producing papillary neoplasm

SPN

Solid + cystic

Hemorrhage; Poorly cohesive cells

Slide 55 · Anatomic and demographic clues are supportive

Entity

Typical anatomical / demographic pattern

SCN

Tail; Older adults; Female > male

MCN

Tail; Approximately 95% female

IPMN

Head; More frequent in males

SPN

Young females; Large mass

Slide 56 · The mutational profiles are not interchangeable

Entity

Characteristic changes

Invasion-associated changes

SCN

VHL inactivation

Not detailed

MCN

KRAS; RNF43 loss

TP53; SMAD4

IPMN

KRAS; RNF43; GNAS; BRAF

TP53; SMAD4

SPN

CTNNB1 activation

Not detailed

Slide 57 · Behavior determines why classification matters

SCN

MCN / IPMN

SPN

Virtually benign

Potentially invasive

Curative after resection in most

Serous, microcystic

Mucinous, distinct compartments

Solid and cystic

Slide 58 · Teaching case: Incidental microcystic tail lesion

An older patient undergoes abdominal imaging for an unrelated reason.

A pancreatic-tail lesion shows a honeycomb of tiny cysts containing clear fluid.

Question: Which neoplasm is most consistent with this profile?

Educational case

Choose the lesion using morphology, anatomical setting and molecular pattern.

Clinical vignette • not real patient data

Slide 59 · Teaching case: Mucin-filled tail mass

A woman has a painless, slowly growing cystic mass in the pancreatic tail.

Large mucin-filled cavities are lined by columnar epithelium over ovarian-type stroma.

Question: What is the diagnosis and what critical adverse event must be excluded?

Educational case

Choose the lesion using morphology, anatomical setting and molecular pattern.

Clinical vignette • not real patient data

Slide 60 · Teaching case: Mucin-producing duct lesion

A pancreatic-head tumor grows within the main pancreatic duct and produces mucin.

No dense ovarian-type stromal component is identified.

Question: Which entity is favored, and which mutation is especially characteristic?

Educational case

Choose the lesion using morphology, anatomical setting and molecular pattern.

Clinical vignette • not real patient data

Slide 61 · Teaching case: Circumscribed hemorrhagic mass

A young woman presents with discomfort from a large well-circumscribed pancreatic mass.

Solid sheets coexist with hemorrhagic cysts and pseudopapillary projections.

Question: Which entity and dominant molecular alteration fit best?

Educational case

Choose the lesion using morphology, anatomical setting and molecular pattern.

Clinical vignette • not real patient data

Slide 62 · Avoid overcalling a mucinous lesion from sex or site

SCN and MCN both often arise in the tail, but they have different biology.

Female predominance occurs in both, though much stronger for MCN.

Luminal contents, epithelial phenotype and ovarian-type stroma discriminate better.

SCN

Microcystic · clear · glycogen-rich

MCN

Large cysts · mucin · ovarian stroma

Slide 63 · Avoid equating precursor status with invasive cancer

Precursor lesion

Noninvasive phase

Possible invasive transformation

New prognostic context

Conceptual pathway; Arrows denote stated biological or clinical relationships.

Slide 64 · Summary: The four high-yield distinctions

Serous cystic neoplasm

Microcysts · clear fluid · VHL

Mucinous cystic neoplasm

Mucin + ovarian stroma · KRAS / RNF43

Intraductal papillary mucinous neoplasm

Duct-centered mucin · GNAS

Solid pseudopapillary neoplasm

Solid–cystic · hemorrhage · CTNNB1

Slide 65 · Primary reference and interpretation limits

Robbins, Cotran & Kumar: Pathologic Basis of Disease, 11th edition (2026).

Chapter: The Pancreas; section: Cystic Neoplasms.

Diagrammatic depictions are original editable schematics—not histologic or radiologic evidence.

No external guidelines, contemporary management algorithms or staging systems were introduced.