HEMANGIOMA

HEMANGIOMAS
DR AMITHA G, BDS, MDS
ORAL AND MAXILLOFACIAL PATHOLOGY
Hemangiomas are benign proliferations of vessels closely resembling normal vessels. They are
so similar to normal vessels that it is unclear whether they represent vessel malformations, true
neoplasms or hamartomatous overgrowths.
One school of thought is that lesions that have greater numbers of endothelial cells than are
required to line their lumen represent neoplasms; the remainder represent hamartomas.
Under this definition, hemangioendotheliomas would represent true neoplasms; but so would
reactive lesions such as papillary endothelial hyperplasia, while arteriovenous malformations and
juvenile capillary hemangiomas represent hamartomas.
Another school of thought contends that malformations present at birth or those that appear
shortly after birth are all congenital and represent vascular malformations. However , many
vascular lesions may be congenital but subclinical at birth , only to appear years later[e.g
telangiectasias seen Hereditary hemorrhagic telangiectasia ]
Hemangiomas Vascular malformations
Hemangiomas are considered to be benign
tumors of infancy that are characterized by a
rapid growth phase with endothelial cell
proliferation, followed by gradual involution
Vascular malformations are structural
anomalies of blood vessels without
endothelial proliferation.
Not present at birth-manifest within first month
of life.
Result from anomalous development of
vascular plexuses. Present at birth, persist
throughout life.
Have a rapid endothelial cell proliferation in
early infancy,followed by involution over time.
Normal endothelial cell growth cycle that
affects veins, capillaries or lymphatics, and
they do not involute.
F:M :3:1 F:M : 1:1
Vascular channels do not resemble vessels of
origin.
Vascular channels resemble vessels of origin
SYNDROMES ASSOCIATED WITH HEMANGIOMAS :

1. Rendu-Osler-Weber syndrome – Autosomal dominant inheritance, multiple
telangiactasias,occasional GI tract involvement & occasional CNS involvement.
2. Sturge –Weber-Dimitri syndrome – non-inherited & non-familial, port-wine stain and
leptomeningeal angiomas.
3. Kasabach-Meritt syndrome – thrombocytopenic purpura associated with hemangioma,
consumptive coagulopathy, microangiopathic hemolysis, intralesional fibrinolysis.
4. Mafucci syndrome – hemangiomas of mucous membranes and dyschondroplasia.
5. von Hippel-Lindau syndrome –genetic transmission variable , hemangiomas of
cerebellum or retina, cysts of the viscera.
6. Klippel-Trenaunay –Weber syndrome -port-wine stain, angiomatosis of the
extremities.
ETIOLOGY:
One hypothesis says that placental cells such as trophoblasts may be the cell of origin for
hemangiomas.
Therefore, hemangiomas may arise secondary to some event in utero.
Needs further investigation.
The exact nature of these vascular tumors is not known, but it is likely that the majority are
hamartomas rather than neoplastic growths.
PATHOPHYSIOLOGY:
Vascular malformations need to be understood in terms of their embryology and development.
The classic sequence of events – 3 stages:
1. The undifferentiated capillary network stage – The primitive mesenchyme is
nourished by an interlacing system of blood spaces without distinguishable arterial and
venous channels.
Arrest in the development As differentiation progresses, primitive vessels
of mesenchyme penetrate deeper into subcutaneous layer, muscle
or bone tissue.
CAPILLARY HEMANGIOMA

2. The retiform developmental stage – Begins at about 48 days of development. Separate
venous and arterial stems appear on either side of the capillary network.
Termination of development Because this stage is characterized by an established
venous, arterial & capillary system.
VENOUS, ARTERIAL OR CAPILLARY MALFORMATIONS
3. The final developmental stage – Begins at 2 months of development and involves
gradual replacement of the immature plexiform network by mature vascular channels.
Aberrations in this stage Maturation of venous & lymphatic systems
predominates.
VENOUS MALFORMATIONS & LYMPHANGIOMAS
• Proliferating hemangioma shows Estradiol -17 beta receptors in the cytoplasm,
corticosteroid treatment theorized to block these receptors.
• Therefore steroids – first line of treatment for proliferating lesions.
• Estradiol receptors absent in stable/ involuting lesions.
Cellular markers to distinguish the phases of hemangioma :
Tissue metalloproteinase (TIMP-1), bFGF, Proliferating Cell Nuclear
Antigen(PCNA), type 4 collagenase, VEGF and Urokinase .
• The basic structure of all these proliferations is an organized formation of complete
intercellular lumina, mantled by pericytic cuffs of variable thickness and lined
with bland endothelial cells with a spectrum of appearances.
• Another feature common to all the hemangiomas (possibly except infiltrating and
targetoid lesions) is a lobular configuration.
• Discrete groups of lesional blood vessels and investing pericytes are separated from
one another by fibrous stroma and contain a central feeder vessel in each lobule.
SALIENT HISTOPATHOLOGIC FEATURES OF VASOFORMATIVE TUMORS
[HEMANGIOMA & VASCULAR MALFORMATIONS] ARE AS FOLLOWS:
HEMANGIOMAS [Proliferative phase]

• Endothelial cell hyperplasia.
• Thickened [multilaminated] endothelial basement membrane.
• Ready incorporation of tritated thymidine in endothelial cells.
• Presence of large number of mast cells.
HEMANGIOMAS[Involuting phase]
• Less mitotic activity.
• Little or no uptake of tritated thymidine in endothelial cells.
• Foci of fibrofatty infiltration.
• Normal mast cell counts.
VASCULAR MALFORMATIONS
• No endothelial cell proliferation.
• Contain large vascular channels lined by endothelium.
• Unilamellar basement membrane.
• Does not incorporate tritated thymidine in endothelial cells.
• Normal mast cell counts.
Hemangiomas:
• Most common tumors of infancy, F:M : 3: 1 and they occur more frequently in whites
than in other racial groups.
• Most common location is the head and neck- 60% of all cases.
• 80%- single lesions, but 20% of affected patients will have multiple tumors.
• Fully developed hemangiomas are rarely present at birth , although a pale macule with
threadlike telangiectasias may be noted on the skin.
• During the first few weeks of life, the tumor will demonstrate rapid development that
occurs at a faster pace than the infant's overall growth .

• Superficial tumors of the skin appear raised and bosselated with a bright- red color -
STRAWBERRY HEMANGIOMA
- They are firm and rubbery to palpation and the blood cannot be evacuated by
applying pressure.
• Deeper tumors may appear only slightly raised with a bluish hue.
• The proliferative phase usually lasts for 6 to 10 months after which the tumor slows in
growth and begins to involute.
• The color gradually changes to a dull -purple hue and the lesion feels less firm to
palpation. By age 5 most of the red color is usually gone.
• About 50% of all hemangiomas will show complete resolution by 5 years of age with
90% resolving by age 9.
• After tumor regression is complete normal skin will be restored in about 50% of patients;
however up to 40% of affected individuals will show permanent changes such as
atrophy, scarring, wrinkling or telangiectasias.
• The most common complication is ulceration, which may occur with or without
secondary infection.
A. CAPILLARY HEMANGIOMA :
This hemangioma is a vascular malformation of a series of abnormal vessels fed by a single
normal arteriole and therefore is not under abnormally high pressure and does not pose a
bleeding threat.
Clinical features:
• Most common benign vascular tumor of infancy.
• Commonest location – skin and soft tissues, especially in head and neck area.
• F>M
• In infants, lesion is also known as cellular hemangioma of infancy, infantile
hemangioendothelioma, strawberry nevus or juvenile hemangioma.
• Presents at birth or shortly thereafter as a red-purple macule with a thin overlying skin
that slowly becomes raised , that tends to regress (70% cases) in months to years.
• Painless, it may ulcerate if the thin overlying skin is ruptured.

• As the lesion regresses, it loses its red to violaceous color and takes on a pale appearance.
• Because the involutional process is one of interstitial and vessel fibrosis, it leaves behind
a firm, fibrotic, multinodular texture. This classic appearance and evolution – strawberry
nevus.
• Large lesions usually disfiguring & can be associated with high morbidity if located near
vital structures.
• Gnepp - The salmon patch variety is faintly pink to rust in color, is flat on the skin
surface, and does not regress spontaneously.
Histology:
• Consist of proliferative vascular channels that are lined by endothelium and lack a
muscular coat.
• Low power – Pattern is multilobular since capillaries proliferate around a feeder
vessel.
• Early lesions : Lobules are highly cellular composed of mitotically active ,
numerous plump endothelial cells forming tiny rounded ,uncanalized vascular
spaces(Indistinct vascular lumina) – Juvenile hemangioma .
• Mast cells, which may be a source of angiogenic factors, can be seen.
• Mature lesions – vessels become canalized , more easily recognized , show
congested lumina and flat endothelial cells.
• As the lesion matures, the endothelial cells become flattened, and the small ,
capillary - sized vascular spaces become more evident .
• A small feeding vessel is found in the vicinity of the tumor.
• Older lesions become fibrotic with complete regression or absence of vascular
elements.
• As the hemangioma undergoes involution, the vascular spaces become more
dilated (cavernous) and widely spaced.
• Perineural invasion not uncommon- doesn’t imply malignant behavior.

• Features that may confuse with malignant behavior - mitotic activity,
intraluminal papillary tufting and proliferation of vessels within perineural
spaces.
Diagnosis :
• Reticulin stain – in immature solid lesions , to highlight the tubular vascular
architecture.
• Demonstration of actin-positive pericytes around individual vascular channels – helpful
in excluding malignancy .
Immunohistochemistry :
• Characterized by expression of GLUT-1 and LeY.
• GLUT-1 – Erythrocyte –type glucose transporter is expressed at all stages of their
evolution.
• These lesions are also composed of CD-133 positive endothelial progenitor cells.
Differential diagnosis :
• Angiosarcoma - Capillary hemangiomas, whether deep or superficial, do not develop
the freely anastomosing sinusoidal pattern encountered in most well-differentiated
angiosarcomas, nor do they manifest nuclear pleomorphism or hyperchromatism.
- The location - Most superficial angiosarcomas are located in the scalp of an elderly
person, and angiosarcoma of the deep soft tissues is quite rare.
• Vascular malformations – GLUT-1 is not expressed by these .
Variations of capillary hemangioma :
1. Tufted angioma [angioblastoma of Nakagawa] – Highly distinct benign vascular tumor
closely related to capillary hemangioma, in which the lobules of tumor cells project into
ectatic but preexisting dermal veins and lymphatics
Clinical features –
• Acquired lesion most often on the neck or trunk of small children, but rarely on mucosal
sites.
• No sex predilection.

• Congenital presentation & familial predisposition – rare.
• Lesions progress slowly over the years as ill-defined red/brown macules, papules and
nodules – tender.
• Clinical course – benign , complete excision not possible because of the extensive nature
of the disease process.
• Local recurrence common.
• Associated with Kasabach-Merritt syndrome and vascular malformation.
Histologic appearance :
• Cardinal feature –Low power - presence of scattered round or ovoid lobules of closely
packed capillaries in the dermis and superficial subcutis in a typically discohesive
“cannonball” distribution.
• Individual lobules similar to those seen in the early stages of strawberry nevus & consist
of varying proportions of poorly canalized bloodless capillaries surrounded by pericytes.
• Endothelial cells are bland and mitotic figures rare.
• Focally , cytoplasmic crystalline inclusions can be seen in the endothelial cells.
• Distinctive feature – Presence of dilated, crescent shaped , lymphatic-like vascular
channels at the periphery of some of the tumor lobules.
• Intravascular location has been described
• In rare cases there is histologic overlap between kaposiform hemangioendothelioma and
tufted angioma.
Differential diagnosis:
• Nodular Kaposi sarcoma – Tufted angioma can be easily distinguished by its
“cannonball” pattern, lack of significant spindle cell population and vasoformative
reticulin pattern.
• Kaposiform hemangioendothelioma – It is a larger or more extensive lesion in which
the lobules are more confluent.
2. Verrucous hemangioma –

Clinical features :
• Presents as a warty blue-black lesion in the lower extremities of children.
• Local recurrence common- wide surgical excision.
Histologic appearance:
• Numerous dilated capillaries and occasional cavernous –like vascular spaces in the
superficial dermis, extending into the deeper dermis and subcutaneous tissue.
• Overlying epidermis shows marked acanthosis & hyperkeratosis.
• Superficial resemblance to Angiokeratomas .
Angiokeratomas represent vascular ectasias, involve only papillary dermis & are
cured by simple excision.
According to GNEPP - Verrucous hemangioma is a variant of cavernous
hemangioma that is typified by overlying epidermal papillomatosis, parakeratosis,
and hyperkeratosis.Keratinocytic rete ridges extend downward in this tumor to
“embrace” or surround lesional blood vessels, much in the same manner as that
observed in angiokeratomas.
3. Cherry angioma[senile angioma/Campbell de Morgan spot] –
Clinical features :
• Very common and present as red papules on the trunk and upper limbs of middle-aged &
elderly adults.
• They increase in number with age.
• Dilated & congested capillaries, with a lobular architecture , situated in papillary
dermis.
4. Lobular capillary hemangioma [Pyogenic granuloma]
• Very common vascular lesion of skin and mucous membranes .

• It was considered as a reactive or infective process based on the presence of
extensive superficial secondary inflammatory changes (due to frequent ulceration)
and an apparent association with trauma 1/3rd
of the cases.
• The underlying process , is however is a lobular vascular proliferation, which
appears to be neoplastic , has deep & intravascular counterparts & has been
redesignated as LOBULAR CAPILLARY HEMANGIOMA.
Clinical features :
• Lesions appear at any age, no sex predilection.
• Predilection for fingers & head and neck area, especially nasal & oral mucosae.
• Congenital lesions – rare.
• Classic appearance – Red nodule < 2cm in diameter.
• Disseminated /”eruptive” pyogenic granuloma – rare.
• “Satellitosis “ – development of recurrence characterized by multiple sessile nodules on
trunk of children & young adults.
• May occur within port-wine stains .
• Pyogenic granuloma-like lesions associated with therapy with capecitabine, topical
tretinoin & isotretinoin.
• Exophytic, ulcerated and surrounded by an acanthotic epidermal collarette.
• Near the surface if ulcerated then, there is a prominent acute inflammatory cell infiltrate
& exuberant , often edematous granulation tissue.
• Core – shows lobules of small capillaries ,with/ without discernible lumina , lined by
prominent endothelial cells.
• Stroma – it is loose & edematous. Numerous normal mitotic figures especially in
mucosal lesions.
• Moderate cytologic atypia – in lesions arising in mouth & conjunctiva ,striking adjacent
to an ulcerated surface & is reactive in nature.
• Rarely epithelioid endothelial cells – seen focally lining the vascular spaces.

• Older lesions – show marked fibrosis.
• Resemblance to granulation tissue is lost in deep or intravascular lesions.
• Satellite nodules show similar histologic findings with involvement of reticular dermis
and even subcutis.
Diagnosis :
• Immunostaining with Actin highlights a layer of pericytes surrounding each individual
blood vessel.
Variants of lobular capillary hemangioma :
1. Granuloma gravidarum
• It refers to similar lesions occurring in gingivae of pregnant women, which usually
involute after delivery.
2. Subcutaneous pyogenic granuloma
• Asymptomatic nodule mainly in the upper limb, identical histologic features without
secondary changes associated with classic pyogenic granuloma.
3. Intravenous pyogenic granuloma
• Rare variant, in adults, in neck & upper extremity.
• Secondary inflammatory changes not seen, clinical behavior is benign.
4. Acquired tufted hemangioma - another subtype of lobular capillary hemangioma, in
which the lobules of tumor cells project into ectatic but preexisting dermal veins and
lymphatics .This arrangement yields a low-power appearance that has been likened to
“cannonballs in the dermis” by Wilson-Jones and Orkin.
Differential diagnoses of Lobular capillary hemangioma :
1. Well differentiated Angiosarcoma
• Poor circumscription, cellular atypia and dissection of collagen bundles.
2. Nodular Kaposi sarcoma
• Prominent spindle cell component with formation of slit-like spaces.
3. Bacillary angiomatosis

• It is an infectious vascular proliferation caused by a Gram-negative organism,
Bartonella henselae & less commonly B.quintana. Occurs exclusively in patients with
AIDS or other immunosuppressive conditions.Responds to antibiotics –erythromycin.
• Architecture of both conditions similar.
• Differences being
In bacillary angiomatosis –
a. Pale epithelioid endothelial cells.
b. Focal cytoplasmic vacuolation .
c. Clusters of polymorphs with leucocytoclasis throughout the lesion
d. Granular basophilic /amphophilic material in relation to the inflammatory cells.
e. When stained with Warthin-Starry or Giemsa – it shows aggregates of short
bacilli.
B. CAVERNOUS HEMANGIOMA
Clinical features :
• Less common, same age, sex and anatomic distribution as capillary hemangioma.
• As opposed to capillary hemangioma, they are larger , diffuse, deeper, less well-
circumscribed and only partially involute.
• Therefore, they persist into adult life unchanged or somewhat fibrosed.
• Any organ in the body can be affected and very few show tendency to regress.
• Classic appearance : soft,diffuse,puffy mass in the parotid, skin over parotid region as
well as within bone, mostly posterior mandible.
• Oral mucosa – large ,soft, blue-red painless blanching mass.
Associated syndromes –
• Mafucci syndrome.
• Kasabach –Merritt syndrome.

• Blue rubber bleb nevus syndrome.
Radiologic features :
• Cupped-out type of resorption of the bony cortex.
• Although these lesions do not undergo involution, they develop calcifications via
phlebolith formation.
• These dystrophic calcifications in organized thrombi are often first seen on a radiograph.
• Central cavernous hemangiomas within bone cause a painless expansion & a mixed
radiolucent-radio-opaque appearance due to stimulation of reactive bone.
• Poorly circumscribed , irregularly dilated blood vessels lined by flat endothelium and
with walls of varying thickness.
• Areas resembling capillary hemangioma seen focally, especially in the superficial
portions.
• Calcifications and formation of phleboliths occur through dystrophic calcification of
organizing thrombi, but regression does not occur.
• Mild inflammation frequently found.
Variants of cavernous hemangioma :
1. Sinusoidal hemangioma
Clinical features:
• Wide anatomic distribution with predilection for subcutaneous tissue of the
breast.[may be confused with Angiosarcoma]
• Middle aged adults, predominantly females.
• Superficially located blue nodule.
• Lesions are lobular, relatively circumscribed and composed of irregular, dilated and
congested , thin walled gaping blood vessels with a typical sinusoidal or sieve-like
pattern.

• Cross-sectioning of back to back blood vessels with little intervening stroma results in
prominent pseudopapillary structures , reminiscent of Masson’s tumor
• The vascular spaces are lined mainly by an attenuated monolayer of endothelial cells,
which can be focally prominent with mild reactive nuclear hyperchromasia.
• An outer layer of actin-positive pericytes can also be discerned.
• Thrombosis with dystrophic calcification as seen in cavernous hemangioma.
• Central infarction – rare.
• Old lesions show fibrosis and hyalinization of blood vessels.
a. Histologic d/d -Well differentiated angiosarcoma – especially in lesions occurring in
the breast.
Mammary angiosarcoma is intraparenchymal rather than dermal/ subcutaneous , shows a
clearly infiltrative or dissecting pattern with at least focal nuclear pleomorphism &
endothelial multilayering.
b. Clinical d/d
- Lymphangioma – as they too are soft & diffuse and can impart a red-blue
appearance by virtue of their hemangiomatous components,some blood in their
abnormal lymphatic spaces & the bluish color of lymph when viewed through skin.
- Neurofibromas & lipomas – resemble because they have a soft, diffuse & irregular
quality to their presentation.
c. Radiographic d/d –
- Fibrous dysplasia & bone tumors .
- Ossifying fibroma or an osteoblastoma.
- In the jaws, may be confused with a developing odontoma, a calcifying odontogenic
cyst or calcifying epithelial odontogenic tumor.
Vascular malformations:

In contrast to hemangiomas, vascular malformations are present at birth and persist throughout
life. Port wine stains are relatively common capillary malformations that occur in 0.3% to 1% of
newborns, most common on the face, particularly along the distribution of the trigeminal
nerve.In SturgeWeber angiomatosis associated intracranial lesions are present.
Port wine stains are typically pink or purple macular lesions that grow commensurately with the
patient . As the patient gets older. the lesion often darkens and becomes nodular because of
vascular ectasia.
a. Low-flow venous malformations encompass a wide spectrum of lesions from small
isolated ectasias to complex growths that involve multiple tissues and organs. They are
present at birth although they may not always be immediately apparent.
- Typicall y, venous malformations have a blue color and are easily compressible. They
often grow proportionately with the patient but they may swell when dependent or
with increased venous pressure. Secondary thrombosis and phlebolith formation can
occur.
b. Arteriovenous malformations are high-flow lesions that result from persistent direct
arterial and venous communication. Although present from birth , they may not become
noticeable until later in childhood or adulthood. Because of the fast vascular flow through
these lesions a palpable thrill or bruit often is noticeable. The overlying skin typically
feels warmer to touch. Presenting symptoms may include pain, bleeding . and skin
ulceration.
c. lntrabony vascular malformations/Intrabony "hemangiomas"- also may occur and
represent either venous or arteriovenous malformations.
- In the jaws, such lesions are detected most often in patient s between 10 and 20 years
of age.
- F>M ; occur twice as often in the mandible as the maxilla .
- The lesion may be completely asymptomatic although some examples are associated
with pain and swelling.
- Mobility of teeth or bleeding from the gingival sulcus may occur.
- A bruit or pulsation may be apparent on auscultation and palpation.
- Radiography : appearance of intrabony is variable. Most commonly, the lesion
shows a multilocular radiolucent defect.
- The individual loculations may be small (honeycomb appearance) or large (soap
bubble appearance).

- In other cases, the lesion may present as an ill-defined radiolucent area or a well-
defined cyst like radiolucency
- Large malformations may cause cortical expansion, and occasionally a "sunburst"
radiographic pattern is produced.
- Angiography can be helpful in demonstrating the vascular nature of the lesion
C. ARTERIOVENOUS HEMANGIOMA[ ARTERIOVENOUS MALFORMATION]
Controversy – AV hemangioma is a term used in the past to describe deeply situated vascular
lesions composed of both veins and arteries, often with AV shunting. Most lesions
designated as AVH have the features of intramuscular hemangioma or angiomatosis. For this
reason, the term AV hemangioma is seldom used as a pathological diagnosis.
Genetics - Majority of AV malformations occur sporadically. Few are familial CMC1 locus
on 5q which is important in capillary hemangiomas are important here also. This suggests
that similar mutations could have different phenotypic expression depending on the vessels
affected.
- Most serious of all hemangiomas & life-threatening.
- The patient is often able to hear a “whirring sound’ or will claim to hear their
heartbeat within the lesion. Some demonstrate a visible palpation or a palpable thrill.
- Those occurring in deep locations or centrally within bones of jaw & bone are
associated with a variable number of direct arteriovenous communications.
- They may also have a large soft tissue component located within overlying skin & lip.
- Most will occur in the maxilla, mandible or tongue in teenage & early adult years.
- Lip – Vague paresthesias due to pulsatile pressure on the inferior alveolar nerve.
- Tongue – Engorgement of the lingual veins on the ventral aspect.
- In high-flow lesions ,jugular venous distension can be seen.
Clinical features:
• It is an uncommon lesion.
• According to the depth of involvement:-
1. Deep type- Usually presents in head & neck or limbs of adolescents & young
adults..

• Associated with severe degrees of arteriovenous shunting and soft tissue hypertrophy.
• Symptoms can be severe & patients can present with cardiac failure & Kasabach –
Merritt syndrome.
• Clinicopathologic correlation , including arteriographic studies very important for
diagnosis.
2. Superficial type [Cirsoid aneurysm/Acral arteriovenous tumor]
• Presents in skin of head & neck [of lip]
• Middle aged or elderly adults – males, as a small red-blue papule.
• Symptoms are minimal include pain & intermittent bleeding.
• Shunting is not a major feature.
Radiographic features :
• Central lesions – Expansion of bone & a fine multilocular radiolucency.
• It varies from distinctly radiolucent to a well-defined multilocular appearance [ “soap-
bubble” to a fine , mixed radiolucent-radio-opaque appearance that resembles fibrous
dysplasia.
• Periosteal new bone formation perpendicular to the cortex , which on occlusal radiograph
shows a sun-ray appearance more often associated with osteosarcoma.
• Periodontal bone loss around one or more teeth, which appear to be elevated in their
sockets.
PATHOGENESIS OF ARTERIOVENOUS HEMANGIOMAS :
Fetal endothelial cell precursors
Lose their ability to
produce/secrete

PDGF &TGF‐β1
[Recruit adventitial cells around developing vessels]
Daughter cells and eventually the vessels that arise from these original cells
Develop into
single cell‐lined vessels (arteries, arterioles, veins, venules)
During prepuberty there is usually insufficient pressure to cause these structurally
unsupported vessels to expand and produce symptoms.
However, beginning at 10 years of age, the maturity of the cardiovascular system and the
increased systemic pressure causes these single cell‐lined vessels to expand.
As they expand, they create turbulence and a negative pressure that reverses the local flow
dynamics to feed blood into these expanded lumen and even recruit new feeder vessels.
This process is known as the BLACK HOLE PHENOMENON.
The black hole phenomenon explains the clinical presentation of patients who are mostly in
their early teenage years and the absence of any limitation to a known vascular anatomy.

The earlier in fetal development that the loss of these growth factors occurs, the larger the
vascular territory that will be involved. Therefore, some will be smaller and some larger in
area; most will cross the midline. This pathogenesis also identifies the arteriovenous
hemangioma as a developmental malformation rather than a neoplasm. Therefore, its
apparent growth during its active phase is not due to a neoplastic process but to either a
further manifestation of developmentally unsupported vessels or to recruitment of vessels
into its central nidus.
Histologic appearances :
• Superficial lesions tend to be better circumscribed than deep lesions.
• Both variants show a mixture of thick- and thin-walled blood vessels that correspond to
arteries & veins of varying caliber with a predominance of the latter.
• Focally some tumors resemble cavernous or capillary hemangiomas.
• Serial sections are helpful in demonstrating arteriovenous anastomosis.
• Focal thrombosis & stromal calcification are sometimes seen.
D. Microvenular hemangioma
• Distinctive cutaneous hemangioma ,a form of acquired venous hemangioma.
• Young adults , red or bluish papules especially in the limbs.
• Occurrence in children rare, recurrence rare.
Histological findings :
• Tumor is composed of irregular branching, thin-walled venules lined by a monolayer of
endothelial cells with plump nuclei, occupying superficial & deep dermis and surrounded
by sclerotic collagen bundles.
• Vessels show angular ramification through the dermis & have an outer layer of pericytes.
• A more lobular component may be evident in the base of the lesion.

E. Hobnail hemanagioma/Targetoid-hemosiderotic hemangioma
Distinctive vascular tumor presents on neck & extremities of young & middle aged patients ,with
male predilection.
Histological findings :
• In superficial dermis – there are irregular dilated thin –walled vascular channels lined by
distinctive ,bland hobnail endothelial cells with focal papillary projections.
• As the lesion extends deeper into the dermis, the endothelial cells become flatter &
narrower vascular channels dissect between collagen bundles.
• Stroma – surrounding stroma shows extravasated RBCs and hemosiderin deposition.
Epithelioid hemangioma (Angiolymphoid hyperplasia with eosinophilia/pseudo or atypical
pyogenic granuloma)
It represents the benign end of the spectrum of a family of vascular tumors characterized by
epithelioid endothelial cells , which includes the recently described cutaneous epithelioid
angiomatous nodule and , at the malignant end of the spectrum, epithelioid
hemangioendothelioma and epitheliod angiosarcoma.
Clinical features :
• It typically presents as single or multiple cutaneous red nodules in the head and neck
area[especially around the ear]
• Middle aged adults, male predilection.
• Oral sites – oral mucosa, tongue.
• In contrast to Kimura’s disease, there’s generally no lymph node involvement.
• Local recurrence.
Histological appearances :
• Partially lobular architecture.

• Lesions are fairly well-circumscribed composed of numerous small to medium-sized,
thin-walled blood vessels lined by plump cells
• Plump cells - copious eosinophilic cytoplasm & oval vesicular nuclei with inconspicuous
nucleoli.
• The epithelioid endothelial cells protrude into the vascular lumina in “hobnail” or
“tombstone” fashion.
• These cells show cytoplasmic vacuoles that,if confluent can form vascular lumina.
• Mitotic figures uncommon, pleomorphism not a feature.
• Thicker blood vessels show myxoid change & solid aggregates of epithelioid cells can be
seen.
• Origin from a small artery or vein is common.
• Surrounding the blood vessels , there is often a prominent inflammatory infiltrate
composed of histiocytes,lymphocytes,plasma cells mast cells & eosinophils.
• Occasionally there is a germinal center formation but less frequent than in Kimura’s
disease.
Variant : Intravenous atypical vascular proliferation
• Young to middle-aged adults.
• Solitary nodule in the head & neck region / upper limb.
Point in contrast to epithelioid hemangioma:
Prominent spindle cell (pericytic) component( closely admixed with the epithelioi
endothelial channels), which enhances the pseudomalignant appearance of these
lesions.
1. Kimura’s disease :
c/f-
a. Affects young oriental males
b. Lymphadenopathy ,eosinophilia and other systemic features of an immunologically
mediated disorder.

H/P
a. Lesions are deeper
b. Show more fibrosis
c. Do not show epithelioid endothelial cells lining the blood vessels.
d. Eosinophil microabscesses are common.
2. Bacillary angiomatosis
a. Shows epithelioid cells with pale cytoplasm & numerous neutrophils.
b. Associated with basophilic clusters of bacteria.
3. Epithelioid hemangioendothelioma
• It has a prominent myxoid or hyaline stroma .
• Tumor cells are arranged in cords or nests,generally lacking formation of overt
vascular channels.
F. Venous hemangioma
Venous hemangiomas occurring in skeletal muscles are best classified as examples of
Intramuscular hemangioma.
Histopathology :
• Tumors are composed of numerous ,irregular , dilated or congested muscular veins,
which are occasionally thrombosed.
• Dystrophic calcification sometimes seen within thrombi.
• Focally tumor resembles a cavernous hemangioma.
Spindle cell hemangioma [formerly Spindle cell hemangioendothelioma]
It is a non-neoplastic lesion associated with either abnormalities of local blood flow
or else a vascular malformation. Hence the revised nomenclature.
Clinical features :

• Solitary ,or often multiple painful , red –blue nodules in the dermis or sub cutis of
distal extremities – hands.
• Lesions may occur in the skeletal muscle – rare.
• No sex predilection,age- 2nd
-3rd
decade of life.
Histologic findings :
• Poorly circumscribed and consists of irregular, cavernous thin-walled vascular spaces
intermixed with solid areas composed mainly of spindle-shaped cells.
• Predominantly intravascular, affecting mainly medium-sized veins.
• In the periphery of the tumor, thick-walled muscular vessels which often show
fibrointimal thickening , reminiscent of an arteriovenous malformation, are commonly
seen.
• Cavernous spaces are lined by an attenuated monolayer of endothelial cells and show
organizing thrombus with frequent phleboliths.
• Papillary projections superficially resembling Masson’s tumor but clearly more cellular
are present.
• Solid areas – Composed of
A. Bland spindle cells with scanty eosinophilic cytoplasm & elongated or plump
rounded nuclei.
B. Epithelioid cells few in number, variable numbers of which show large
intracytoplasmic vacuoles.
- Slit-like vascular spaces also found in the solid areas.
- Bundles of smooth muscle cells around dilated vascular spaces as well as in the solod
areas.
- Rarely there is focal degenerative endothelial atypia.
Immunohistochemistry :

• The cells lining the vascular spaces & the epithelioid cells in the solid areas –
stain for endothelial markers.
• Spindle cells –
- Stain for vimentin
- A small percentage for actin and/or desmin.
Nodular Kaposi Sarcoma Spindle cell hemangioma
Cavernous spaces & epithelioid vacuolated
cells absent
Cavernous spaces & epithelioid vacuolated
cells present.
Cytoplasmic hyaline globules in spindle cells
present
Cytoplasmic hyaline globules in spindle cells
absent.
IHC- Spindle cells express HHV-8 IHC- Spindle cells express vimentin, few also
express desmin &/or actin.
G. DEEP HEMANGIOMAS :
1. Intramuscular hemangioma :
Clinical features :
• Uncommon deeply located soft tissue tumor.
• Adolescents & young adults, no sex predilection.
• Sites – Lower limb followed by head & neck , upper limbs & trunk.
• Typical lesion – slowly growing mass, often painful especially on exercise.
• Congenital in origin, not associated with trauma.
Radiologic findings :
• Soft tissue calcification , corresponding either to phleboliths or metaplastic ossification.

Histologic appearances :
Classification – according to vessel size & predominant blood vessel type.
1. Small (Capillary)
2. Large (Cavernous)
3. Mixed
• In practice , most lesions appear to be of mixed type – consist of capillaries ,veins,small
arteries and even lymphatic –like channels.
Pure intramuscular capillary hemangiomas – head & neck area.
Intramuscular lymphangioma – seen in trunk.
• Associated variable amounts of mature fat [therefore were previously called infiltrating
angiolipomas]
• Stroma – Degenerative or reactive sarcolemmal nuclei.
Intramuscular lipoma Intramuscular angioma
Indolent course with less tendency to recur Recurrence rates high.
Prominent vascular component absent Prominent vascular component present.
Angiosarcoma Intramuscular angioma
Lobular architecture absent Lobular architecture present
Presence of endothelial atypia or multilayering Absence of endothelial atypia or multilayering
2. Synovial hemangioma

Clinical features:
• Uncommon lesions that arise in the intra-articular space, bursae & tendon sheath.
• Present in young adults or children, males.
• Slowly growing asymptomatic or painful mass ,affecting especially the knee & elbow.
• Benign, no tendency to recur.
• Half of the cases of synovial hemangioma represent cavernous lesions & rest are
examples of capillary hemangioma, arteriovenous hemangioma & pure venous
hemangioma.
3. Intraneural hemangioma
Clinical features :
• Uncommon, related to the nerve involved and include pain, paresthesiae & numbness.
• Extensive epineural, perineural & endoneurial involvement can occur & associated with
significant morbidity.
• Histologically most lesions are cavernous hemangiomas.

HEMANGIOMA

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HEMANGIOMA