Hemangiomas and Vascular Malformations

Slide 1 · Hemangiomas and Vascular Malformations

Pathogenesis · morphology · clinicopathologic interpretation

Dr Abu Suraih Sakhri

MBBS, MD (Pathology)

www.abusuraihsakhri.com

Slide 2 · Learning objectives

Separate proliferative vascular tumors from structural malformations.

Recognize capillary, juvenile, cavernous, and lobular capillary patterns.

Explain clinically important ectasias and lymphatic lesions.

Distinguish cerebral arteriovenous from cavernous malformations.

Slide 3 · Two fundamentally different vascular lesions

Vascular tumors form masses through endothelial proliferation.

Vascular malformations comprise structurally abnormal vessels.

Both may appear red-blue and mass-forming at the surface.

Biologic category—not color alone—determines interpretation.

Mass-forming vascular lesion

Proliferative tumor

Structural malformation

Endothelial growth

Abnormal channel arrangement

Slide 4 · Why the word “hemangioma” is ambiguous

In strict usage, hemangioma designates a benign vascular tumor.

Historical usage also labels some malformations “hemangiomas.”

Similar appearance and architecture encourage diagnostic overlap.

Describe the lesion and its biologic behavior before naming it.

Slide 5 · Pediatric vascular lesions: Typical topography

These are the commonest mass-forming lesions of infancy.

Skin is a frequent site, particularly the face and scalp.

Visible lesions range from flat patches to elevated masses.

Color is commonly red to blue, with irregular contours.

Face / scalp

Frequent superficial sites

Slide 6 · Surface appearance is a continuum

A flat colored patch may represent ectatic vessels.

An elevated mass may contain proliferating vascular channels.

Superficial color does not reliably reveal deep extent.

Depth and tissue relationships require separate consideration.

Varying visible elevation

Flat ectasia

Raised vascular mass

Slide 7 · Natural history can distinguish entities

Some childhood hemangiomas initially enlarge and later involute.

Persistent port-wine stains behave differently from regressing lesions.

Cavernous lesions generally do not regress.

A time course adds information beyond a single examination.

Proliferation

Plateau / regression

Persistence

Different lesion types follow different courses

Slide 8 · Vascular tumor versus malformation

Feature

Proliferative tumor

Vascular malformation

Primary process

Vascular endothelial growth

Abnormal vessel architecture

Term “hemangioma”

Strictly appropriate for benign tumor

Sometimes applied historically

Presentation

May form raised mass

May be flat or mass-forming

Interpretation

Morphology + growth pattern

Morphology + vascular configuration

Slide 9 · Why benign childhood masses still matter

Many benign pediatric tumors are clinically inconsequential.

Size and anatomic position can nonetheless cause major problems.

A cosmetically conspicuous lesion may have functional consequences.

Benign histology does not guarantee a harmless clinical course.

Slide 10 · Histologic hallmarks of benign vascular proliferation

Recognizable lumina contain erythrocytes in blood-vessel lesions.

A single layer of bland endothelial cells lines the channels.

Organization as vessels contrasts with solid atypical growth.

The relevant diagnosis still depends on the specific architecture.

Small endothelial-lined blood spaces

Schematic — not a histologic specimen

Slide 11 · What raises concern for malignancy?

Malignant vascular tumors are more solidly cellular.

Cytologic atypia can accompany loss of well-formed lumina.

Normal-looking blood-filled channels favor benign vascular growth.

Ambiguous cases may require demonstration of endothelial lineage.

Slide 12 · Capillary hemangioma: Defining architecture

This is the most common hemangioma type.

The lesion contains numerous small, thin-walled capillaries.

Supporting stroma is relatively scant.

The compact capillary network explains its often red appearance.

Small endothelial-lined blood spaces

Schematic — not a histologic specimen

Slide 13 · Capillary hemangioma: Site distribution

Commonly affects the skin and subcutaneous tissues.

Oral mucosa and lips are frequent superficial locations.

It may also develop in liver, spleen, and kidney.

Site alone does not establish a specific vascular subtype.

Slide 14 · Microscopic reading: Identify the capillary units

Look for multiple small lumina rather than cavernous spaces.

Each lumen is bounded by a thin endothelial lining.

Erythrocytes identify the channels as blood vessels.

This is a native schematic; No patient histology is shown.

Small endothelial-lined blood spaces

Schematic — not a histologic specimen

Slide 15 · Juvenile hemangioma: Dynamic childhood lesion

The “strawberry” variant commonly involves newborn skin.

Lesions may be multiple.

A rapid proliferative phase occurs over the first months.

Regression follows in many cases rather than continuous expansion.

Slide 16 · Juvenile hemangioma: Proliferative-to-involutional course

Early months: Conspicuous enlargement can be rapid.

Fading beginning around ages 1–3 years.

Complete regression is reported by age 7 in most cases.

These age landmarks describe a pattern, not an individual guarantee.

Rapid early growth

Fading (1–3 y)

Regression (often by 7 y)

Illustrative course of juvenile hemangioma

Slide 17 · Why a regressing lesion is not a port-wine stain

Juvenile hemangioma

Port-wine stain

Early course

Proliferative growth

Flat vascular birthmark

Later course

Common spontaneous regression

Usually persists; may thicken

Biologic class

Benign vascular tumor

Vascular ectasia / malformation

Interpretive clue

Changing mass

Persistent patch

Slide 18 · Multiplicity does not imply malignancy

Juvenile cutaneous hemangiomas may be multiple.

Multifocality requires interpretation in anatomic context.

The depth and extent of lesions determine clinical importance.

Do not equate several benign vascular lesions with aggressive histology.

Slide 19 · Hemangiomas may extend beyond the skin

Internal hemangiomas are recognized in the same vascular spectrum.

The liver accounts for a substantial share of internal lesions.

Extensive involvement is sometimes termed angiomatosis.

Specific complications depend on the involved organ.

Slide 20 · Location determines clinical significance

Most superficial lesions are benign and primarily cosmetic.

Ulceration or bleeding may occur with trauma.

Deep lesions can affect nearby structures.

CNS involvement has distinctive neurologic risks.

Skin

Appearance / ulceration

Deep tissue

Mass effect

CNS

Neurologic signs / hemorrhage

Slide 21 · Cavernous hemangioma: Dilated vascular spaces

Large, blood-filled channels dominate the architecture.

Connective tissue separates the cavernous spaces.

Cavernous spaces contrast with the fine capillary pattern.

The description is morphologic; Terminology requires site context.

Large spaces separated by connective tissue

Schematic — not a histologic specimen

Slide 22 · Cavernous hemangioma: Growth pattern

A sharply delineated but unencapsulated lesion.

Cavernous lesions can extend into deeper tissue.

They are more infiltrative than capillary hemangiomas.

Spontaneous regression is generally not expected.

Slide 23 · Cavernous spaces favor stasis-related changes

Dilated vascular spaces may develop intraluminal thrombosis.

Organizing thrombi may undergo dystrophic calcification.

These changes modify the appearance of the mass.

Recognize secondary changes without inferring malignancy.

Thrombus and calcification can form within enlarged spaces

Schematic — not a histologic specimen

Slide 24 · Cavernous hemangioma: Major clinical hazards

Large lesions may produce local tissue compression.

Surface lesions can ulcerate or bleed following trauma.

Cerebral vascular lesions may bleed or cause mass effect.

Clinical significance is strongly site- and size-dependent.

Slide 25 · Capillary and cavernous hemangiomas

Attribute

Capillary

Cavernous

Dominant spaces

Small, thin-walled capillaries

Large, dilated blood-filled channels

Intervening stroma

Relatively scant

Connective tissue septa

Typical depth

Often superficial

Frequently deep

Regression

Some juvenile lesions involute

Generally not spontaneous

Secondary finding

Proliferative capillary pattern

Thrombosis / calcification possible

Slide 26 · Pyogenic granuloma is a vascular proliferation

Despite the name, this lesion is not a pyogenic infection.

It with capillary hemangiomas.

It grows rapidly as a red, often pedunculated nodule.

Skin, gingiva, and oral mucosa are characteristic sites.

Friable pedunculated vascular nodule

Schematic — not a histologic specimen

Slide 27 · Why pyogenic granulomas bleed easily

The lesion is highly vascular and close to the surface.

Surface ulceration is common.

Minor mechanical contact may precipitate bleeding.

A rapidly growing bleeding nodule warrants careful morphologic review.

Slide 28 · Pyogenic granuloma: Associated settings

Some lesions follow local trauma.

A gingival lesion in pregnancy is termed granuloma gravidarum.

Rapid growth can occur over only a few weeks.

Context helps recognition but does not replace tissue diagnosis.

Slide 29 · Pyogenic granuloma: Possible outcomes

Curettage and cautery are often effective.

Some pregnancy-associated lesions regress after delivery.

Other lesions may become fibrotic.

Occasional cases require surgical excision.

Slide 30 · Three patterns within the hemangioma family

Pattern

Defining feature

Characteristic course / symptom

Capillary

Fine vascular network

Often superficial

Juvenile / strawberry

Early proliferative cutaneous lesion

Common eventual involution

Cavernous

Broad, dilated vascular spaces

May persist and involve deep tissue

Pyogenic granuloma

Rapidly growing red pedunculated nodule

Bleeding and surface ulceration

Slide 31 · Vascular ectasia means dilation, not neoplasia

Ectasia signifies localized dilation of a tubular structure.

Telangiectasia is permanent dilation of small preexisting vessels.

The affected vessels may be capillaries, venules, or arterioles.

Congenital and acquired telangiectasias are not true tumors.

Epidermis

Permanently dilated existing vessels

Schematic — not a histologic specimen

Slide 32 · Nevus flammeus: A flat congenital vascular mark

Nevus flammeus is described as a common vascular ectasia.

It forms a light-pink to purple flat head or neck patch.

The underlying process is dilated cutaneous vessels.

Its clinical course distinguishes subtypes.

Slide 33 · Port-wine stain: Persistence is diagnostic context

A port-wine stain is a subtype of nevus flammeus.

It typically persists instead of regressing.

It can enlarge and thicken the overlying skin during childhood.

An otherwise similar flat lesion may have a different time course.

Epidermis

Persistent ectatic vessels beneath flat patch

Schematic — not a histologic specimen

Slide 34 · Port-wine stain: Anatomic pattern can be informative

Facial port-wine stains may follow trigeminal territories.

Some are associated with Sturge–Weber syndrome.

An extensive facial lesion warrants attention to neurologic context.

Anatomic association is not equivalent to syndrome diagnosis.

Slide 35 · Sturge–Weber: Cutaneous and CNS vascular findings

Facial port-wine nevi can coexist with ipsilateral leptomeningeal lesions.

The cortical venous abnormalities can cause neurologic disease.

Seizures, weakness, and developmental impairment are described.

Dermatologic and neurologic findings must be integrated.

Facial port-wine stain

Ipsilateral leptomeningeal vascular lesion

Seizures / focal neurologic effects

Syndromic association; Not inevitable

Slide 36 · GNAQ links some port-wine stains to somatic signaling

Most port-wine stains with activating GNAQ variants.

GNAQ encodes a heterotrimeric G-protein α subunit.

The alteration is somatic rather than necessarily inherited.

A focal genetic alteration can produce a localized vascular phenotype.

Somatic GNAQ activation

Endothelial signal alteration

Focal port-wine phenotype

Slide 37 · Spider telangiectasia: Central core and radial vessels

A central vascular focus gives rise to radiating small vessels.

The lesion often appears pulsatile and blanchable.

Face, neck, and upper chest are common locations.

Its architecture differs from a solid vascular mass.

Radial telangiectatic vessels

Schematic — not a histologic specimen

Slide 38 · Spider telangiectasia and hormonal states

Spider telangiectasias are nonneoplastic dilations.

They occur frequently in hyperestrogenic settings.

Pregnancy and cirrhosis are textbook associations.

The lesion is a clinical clue, not evidence of a specific tumor.

Slide 39 · HHT is an inherited vascular-malformation syndrome

Hereditary hemorrhagic telangiectasia is autosomal dominant.

Defects affect endothelial components of TGF-β signaling.

Dilated capillaries and veins form widespread telangiectasias.

Vascular fragility produces a characteristic bleeding phenotype.

Inherited endothelial pathway defect

Fragile capillary / venous malformations

Epistaxis · GI bleeding · hematuria

Slide 40 · HHT: Mucosal and systemic distribution

Cutaneous and oral mucosal sites are common.

Lesions can involve the respiratory tract.

Gastrointestinal and urinary tracts may also be affected.

Distribution helps distinguish systemic disease from a local patch.

Slide 41 · HHT: Clinical consequences of fragile vessels

Spontaneous epistaxis may be prominent.

Gastrointestinal hemorrhage can be clinically significant.

Urinary-tract lesions may cause hematuria.

Repeated bleeding reflects vessel fragility, not tissue invasion.

Slide 42 · Three vascular ectasia phenotypes

Phenotype

Morphologic clue

Clinical association

Port-wine stain

Persistent flat red-purple patch

Occasional Sturge–Weber link

Spider telangiectasia

Radial vessels around central core

Hyperestrogenic states

HHT

Widespread capillary/venous dilations

Inherited bleeding disorder

Slide 43 · Lymphangioma involves lymphatic rather than blood channels

Lymphangiomas are benign lymphatic counterparts of hemangiomas.

Lymphatic lumina typically lack erythrocytes.

Endothelial lining is still present.

Lymphatic differentiation may be highlighted by specialized markers.

Blood: Erythrocytes

Lymph: Often no RBCs

Schematic — not a histologic specimen

Slide 44 · Simple lymphangioma: Superficial pattern

Simple capillary lymphangiomas can be slightly elevated.

Small pedunculated lesions may also occur.

They preferentially involve head, neck, and axillary regions.

Histology reveals networks of endothelial-lined lymphatic spaces.

Slide 45 · Cystic hygroma: Markedly expanded lymphatics

Cavernous lymphangioma is also called cystic hygroma.

The neck and axilla are characteristic childhood sites.

Large lesions can cause visible regional deformity.

Massively dilated lymphatic spaces define their architecture.

Enlarged endothelial-lined lymphatic spaces

Schematic — not a histologic specimen

Slide 46 · Cystic hygroma: Supporting tissue and margins

Cysts are separated by connective tissue stroma.

Lymphoid aggregates can occur within the intervening tissue.

The lesion is often unencapsulated with indistinct margins.

These boundaries make complete resection challenging.

Slide 47 · A clinicopathologic association: Turner syndrome

Cervical cystic hygromas in Turner syndrome.

The association reflects abnormal lymphatic development.

A neck mass alone cannot establish a chromosomal disorder.

Integrate morphology with the full clinical setting.

Slide 48 · Lymphatic immunophenotype: Interpret the purpose

VEGFR-3 and LYVE-1 are cited lymphatic endothelial markers.

Their purpose is to support lymphatic lineage.

Blood-filled versus lymph-filled spaces provide another clue.

A marker never substitutes for lesion architecture and context.

Slide 49 · Glomus tumor is vessel-associated but not an hemangioma

Glomus tumors arise from modified smooth muscle cells.

They are related to thermoregulatory arteriovenous structures.

Subungual location and marked pain are characteristic clues.

Cell of origin, not vascular appearance alone, is decisive.

Slide 50 · Bacillary angiomatosis: Infectious vascular mimic

This reactive proliferation occurs in immunocompromised hosts.

Bartonella species are the causative pathogens.

Skin, bone, brain, and other sites can be involved.

Recognition redirects interpretation from neoplasia to infection.

Slide 51 · Bartonella-driven angiogenesis has a defined sequence

Bartonella infection can increase tissue HIF-1α activity.

HIF-1α promotes vascular endothelial growth factor production.

VEGF stimulates the local vascular proliferative response.

The process resolves with appropriate antimicrobial treatment.

Bartonella infection

HIF-1α → VEGF

Reactive vessel proliferation

Slide 52 · Endothelial markers solve a specific diagnostic problem

CD31 and von Willebrand factor support endothelial lineage.

Such stains are useful when malignant lesions lose vascular channels.

They do not by themselves distinguish all tumor subtypes.

Morphology and clinical context remain indispensable.

Slide 53 · Vascular lesions span biologic categories

Category

Textbook examples

Key discriminator

Benign endothelial tumors

Capillary / cavernous hemangioma

Organized blood-filled vessels

Nonneoplastic malformations

Nevus flammeus; cerebral AVM

Abnormal established channels

Lymphatic lesions

Simple / cavernous lymphangioma

Lymphatic endothelial-lined spaces

Reactive proliferation

Bacillary angiomatosis

Infectious context

Malignant vascular tumor

Angiosarcoma

Atypical, poorly formed vessels

Slide 54 · Four groups of cerebral vascular malformations

Arteriovenous malformations form one major category.

Cavernous malformations are a distinct low-flow category.

Capillary telangiectasias are a third group.

Venous angiomas form the fourth group.

Arteriovenous

High flow

Cavernous

Low flow

Capillary telangiectasia

Small vessels

Venous angioma

Venous drainage

Slide 55 · Cerebral AVM: High-flow arteriovenous shunting

Abnormal arterial channels connect to the venous side.

Capillary resistance is bypassed within the shunting network.

Blood flow is relatively high and often pulsatile.

The malformation can affect brain or subarachnoid tissues.

Artery

Tangled AV nidus

Vein

Direct abnormal AV connection; No normal capillary bed

Slide 56 · Cerebral AVM: Microscopic organization

Tangled, enlarged vessels form a wormlike network.

Gliotic brain tissue may separate the malformed vessels.

Old hemorrhage can be evident.

Arterial elastic lamina and vessel-wall architecture may be abnormal.

Slide 57 · Cerebral AVM: Major clinical presentations

Seizures can be the first presentation.

Intracerebral or subarachnoid hemorrhage can occur.

A common presentation in ages 10–30.

The middle cerebral artery territory is frequently involved.

Slide 58 · Vein of Galen malformation: Neonatal hemodynamic risk

An arteriovenous shunt can deliver high-pressure blood to veins.

A neonatal vein of Galen lesion may produce a large shunt.

The increased cardiac flow burden can lead to heart failure.

This is a hemodynamic hazard distinct from cosmetic skin lesions.

Artery

High-volume shunt

Vein

Neonatal high-flow burden → cardiac failure

Slide 59 · Cerebral cavernous malformation: Back-to-back channels

Distended vascular spaces cluster directly against each other.

Walls are collagenized and vary in thickness.

Brain tissue is often sparse or absent between channels.

Old hemorrhage, infarction, or calcification may surround the lesion.

Collagenized, adjacent low-flow channels

Schematic — not a histologic specimen

Slide 60 · Cerebral cavernous malformation: Low-flow physiology

Cavernous malformations do not create an arteriovenous shunt.

Their channels carry relatively low-flow blood.

Hemorrhage and focal neurologic effects remain possible.

Physiology distinguishes them from high-flow AVMs.

Slide 61 · Familial cerebral cavernous malformations

Familial forms often feature more than one lesion.

The inherited pattern is autosomal dominant.

Genes include KRIT1, CCM2, and PDCD10.

These genes encode elements of a CCM protein complex.

KRIT1

CCM2

PDCD10

CCM protein complex

Inherited loss of function predisposes to lesions

Slide 62 · CCM signaling and acquired cooperating alterations

Loss of CCM complex function releases restraints on vessel growth.

PIK3CA activating changes in growing lesions.

Both inherited susceptibility and somatic change may participate.

This mechanism should not be generalized to every vascular mark.

CCM complex dysfunction

PIK3CA activation (some lesions)

Abnormal vessel growth

Slide 63 · Cerebral AVM: A different molecular association

Activating somatic KRAS mutations in many AVMs.

Endothelial RAS signaling is implicated in abnormal vessel formation.

This differs from the familial CCM gene complex.

Similar clinical risks do not imply the same molecular mechanism.

Endothelial somatic KRAS

RAS signaling dysregulation

Cerebral AV malformation

Slide 64 · AVM versus cerebral cavernous malformation

Feature

Cerebral AVM

Cerebral cavernous malformation

Hemodynamics

High-flow shunt

Low-flow; no AV shunt

Architecture

Arterial/venous tangle; gliosis

Back-to-back distended channels

Neural tissue between

Often gliotic tissue

Often absent

Molecular association

Somatic KRAS activation

CCM genes; PIK3CA cooperation

Risks

Seizures, hemorrhage, shunt complications

Hemorrhage and local neurologic dysfunction

Slide 65 · Do not conflate VHL lesions with familial CCM

VHL is a separate inherited tumor-predisposition syndrome.

Its characteristic CNS vascular tumors include hemangioblastomas.

Familial CCM instead centers on KRIT1, CCM2, and PDCD10.

Use precise anatomic and pathologic nomenclature.

Slide 66 · An interpretive sequence for a vascular lesion

First establish site, depth, and observed natural history.

Next distinguish proliferative mass from dilated vessels.

Then classify blood-filled, lymphatic, or supportive-cell architecture.

For cerebral lesions, distinguish shunting from low flow.

Site + time course

Vessel class / lumen

Morphology + depth

Shunting / syndromic context

Slide 67 · Case application: Persistent facial patch

A child has a flat red-purple cheek lesion since infancy.

It has not followed a proliferative-then-involutional course.

The lesion has become more conspicuous and thicker over time.

Question: What vascular category best explains this history?

Slide 68 · Case interpretation: Port-wine stain

A persistent flat vascular mark favors nevus flammeus, port-wine type.

Persistence separates it from the usual juvenile hemangioma course.

Facial distribution prompts consideration of associated CNS findings.

The vignette alone does not diagnose Sturge–Weber syndrome.

Slide 69 · Case application: Friable gingival nodule

A young adult develops a rapidly enlarging red gingival nodule.

It is pedunculated and bleeds after minor contact.

There is a possible recent local traumatic trigger.

Question: Which benign vascular pattern is suggested?

Slide 70 · Case interpretation: Pyogenic granuloma

Rapid growth, pedunculation, and bleeding favor pyogenic granuloma.

The name does not imply bacterial suppuration.

Oral location and trauma are compatible supporting clues.

Histologic examination remains relevant if presentation is atypical.

Slide 71 · Case application: Repeated cerebral hemorrhage

A patient has multiple CNS vascular lesions and recurrent focal symptoms.

Imaging suggests low-flow vascular spaces without an AV shunt.

Family history indicates similar lesions in relatives.

Question: Which malformation family and genes merit consideration?

Slide 72 · Case interpretation: Familial CCM

Low-flow clustered channels fit cerebral cavernous malformations.

Multiplicity and family history support a familial form.

KRIT1, CCM2, and PDCD10 are the textbook genes.

This is distinct from an AVM driven by arteriovenous shunting.

Slide 73 · Five discriminators that organize the subject

Proliferation versus malformed preexisting channels.

Small capillaries versus broad cavernous spaces.

Regression versus persistence or deep extension.

Blood-filled channels versus lymphatic spaces.

High-flow AVM versus low-flow cerebral cavernous malformation.

Slide 74 · Source and scope

Primary: Robbins, Cotran & Kumar, Pathologic Basis of Disease, 11th ed. (2026), Chapter 10, pp. 432–433.

Related textbook context: Chapter 11, pp. 472–474, vascular tumors, vascular ectasias and lymphatic lesions.

CNS extension: Chapter 28, pp. 1143–1144, cerebral vascular malformations.

Conceptual drawings are original editable schematics, not diagnostic specimens.