Spindle cell neoplasms are defined as neoplasms that consist of
spindle-shaped cells in the histopathology.
The head and neck is an embryologically and anatomically complex
area, with a number of important structures and organs lying in close
proximity to one another.
The histological diagnosis of spindle cell lesions can be challenging in
any site, but in this region is particularly so, due to the variety of
structures from which they can arise.
Account for less than 1% of all tumors in the oral regions.
Spindle cell tumor is not a specific diagnosis or a specific
type of cancer.
Spindle cell tumor is a descriptive diagnosis based on the
presence of elongated/spindle cells under the microscope.
Spindle cell carcinoma
Variant of squamous cell carcinoma characterized by dysplastic surface squamous
epithelium in conjunction with an invasive spindle cell component which simulate a
true sarcoma but are epithelial in nature. (WHO;2005)
3% of all squamous carcinomas in the head and neck region
Etiology: still under debate.
Other names: Carcinosarcoma, sarcomatoid carcinoma
Polypoid SCC, Lane tumor
‘‘Collision’’ tumors where there are two separate neoplastic clones
combined in the same lesion.
Spindle cells: anaplastic type of carcinoma cell.
Squamous cell carcinoma ‘‘drives’’ the proliferation of a
pseudosarcomatous stromal response.
EM & IHC analysis: spindle cells are of epithelial origin, with the ability to
produce mesenchymal intermediate filaments.
Dysfunctional cadherin-catenin complex: tumor cells shift from a squamous
to a spindled type.
Most of the cases: recurrences after radiotherapy for well differentiated
Common sites: upper aero-digestive tract : larynx, oral cavity & esophagus.
Oral cavity : lower lip, lateral posterior tongue & alveolar ridges.
Typically appears as a pedunculated, polypoid mass; occasionally as sessile,
nodular, fungating mass or as an ulcer.
Pain &paresthesia prominent features.
Tumor grows rapidly, tends to metastasize early; diagnosed in a late stages.
Mean age : 57 years; no sex predilection
(a) Spindled and pleomorphic tumor cells ‘‘dropping off’’ from squamous cell carcinoma in situ;
arrow indicates a tumor giant cell; (b) cellular spindle cell component of a spindle cell carcinoma
with fascicles of relatively regular cells with fusiform nuclei.
Conventional SCC admixed with spindled/pleomorphic tumour cells.
Squamous cell component can range from varying grades of dysplasia to carcinoma-in-
situ or frank SCC with varying grades of differentiation.
Spindle cells show a variety of architectural patterns : fascicles, a storiform pattern, a
‘herringbone’ pattern similar to fibrosarcoma, associated with dense collagen as seen in
fibromatosis or with a nodular- fascitis like appearance.
Direct transition between the two cell types can be seen.
Spindled component – may be bland and regular or markedly pleomorphic, mitotic
figures, multinucleated tumour giant cells.
Metastatic lesions - only spindle cells, only squamous cells or combination.
Bone, cartilage or muscle differentiation may be seen.
Sometimes present as extensively ulcerated masses with tumor cells widely
spaced apart in a loose, pale or myxoid background.
There are frequently abundant small vessels with plump endothelial cells and
numerous inflammatory cells, particularly neutrophils.
Closely mimic exuberant granulation tissue
Cytokeratin, K1, K18
MSA -15%, desmin less than 2%
Malformation of the skin & mucosa that are congenital or developmental.
Arise from the surface epithelium or from any of the connective tissue tissues.
Common recognized nevus – ACQUIRED MELANOCYTIC NEVUS.
Represents a benign, localized proliferation of cells from the neural
crest called NEVUS CELLS.
Neural crest origin.
Ability to produce melanin.
First cousins of melanocytes.
Begin to develop on skin during childhood
Before 35 years of age.
Women > men; whites> blacks.
Site : above the waist; H &N region.
Clinical stages :
JUNCTIONAL NEVUS – sharply demarcated , brown or black macule (< 6 mm)
COMPOUND NEVUS – when nevus cells proliferate to produce a slightly elevated, smooth
surfaced, soft papule. Degree of pigmentation becomes less; appear brown or tan.
INTRADERMAL NEVUS – nevus gradually loses its pigmentation, surface- papillomatous,
hairs are seen growing from the center.
Many of them involute & disappear.
Intra –oral nevi : uncommon; palate, mucobuccal fold, gingiva
Characteristic feature – benign, Unencapsulated proliferation of small, ovoid cells.(nevus
cells); lack the dendritic processes.
Small, uniform nuclei, eosinophilic cytoplasm, indistinct cell borders; produce melanin
Tend to get organized into small, round aggregates (theques)
JUNCTIONAL NEVUS : theques of nevus cells found only on the basal layer of the
epithelium; junction of the epithelium – connective tissue interface.
COMPOUND NEVUS : Nevus cells proliferate to drop off into the underlying connective
tissue; present along the junctional area & within the underlying connective tissue.
INTRADERMAL/ INTRAMUCOSAL NEVUS: nests of nevus cells are no longer found in the
epithelium, but are found only within the underlying connective tissue.
Superficial cells ( TYPE I: EPITHELIOD ) – appear larger & epitheliod; abundant cytoplasm,
frequent intra-cellular melanin & tendency to cluster into theques.
Middle portion ( TYPE II: LYMPHOCYTIC- LIKE ) - less cytoplasm, seldom pigmented,
appear like lymphocytes.
Deeper cells ( TYPE III : SPINDLE SHAPED ) - appear elongated; spindle shaped, like
schwann cells or fibroblasts.
Mucosal malignant melanoma
Malignant neoplasm of neural crest derived melanocytic cells.
Uncommon, accounting for less than 1% of head and neck melanomas.
Most commonly occurs in the nasal cavity and paranasal sinuses, but may also
arise in the oral cavity, larynx and pharynx.
Macroscopically, mucosal melanomas are often polypoid and pigmented
Histologically, ulceration is often present, although intact surface epithelium is
usually identifiable in some areas and pagetoid spread of melanoma cells may be
Like cutaneous melanomas, the malignant cells can show a variety of appearances.
Usually epithelioid or ovoid cells with large nuclei, prominent nucleoli &nuclear
pseudo-inclusions, cytoplasm will be uniformly eosinophilic or clear.
Occasionally, the cells become spindle or desmoplastic in areas..
Desmoplastic melanoma - prominent hyalinized stroma, are amelanotic and often
show perineural invasion.
Nodular fasciitis (Pseudosarcomatous fasciitis)
A benign and reactive fibroblastic growth extending as a solitary nodule from
the superficial fascia into the sub-cutaneous fat and subjacent muscle.
It is closely related to “ proliferative myositis” which occurs in muscle.
Etiology : unknown; trauma ?? Because of the location of the lesions over
bony prominence (angle of the mandible & Zygoma ).
Although considered a reactive condition, recent molecular studies suggests
that the cells are clonal, thus confirms that it is a benign neoplasm.
Trunk &extremities – most commonly involved.
10 % - soft tissues of the head and neck region, usually
presenting as a rapidly enlarging mass.
Rare cases : parotid gland.
Occur in 3- 5th decade of life.
Intra –oral sites: buccal mucosa, tongue and alveolar mucosa
Occur mostly in areas which serve as sites of origin and
insertion of muscles of mastication.
The lesion will be well-delineated but not encapsulated proliferation
of spindle cells inside the lamina propria
A nodular growth contains plump fibroblasts with vesicular nuclei in a haphazard
to storiform arrangement.
Myxoid areas are often found, multinucleated giant cells are occasionally
Found originating from the adjacent muscle or fusion of macrophages.
Spindle shaped cells have large oval nuclei and discrete
Unencapsulated with an infiltrative margin.
The component spindle cells are plump, often pleomorphic and arranged in a
‘tissue culture’ pattern, often with accompanying hemorrhage and scattered lymphocytes.
Mitotic figures are usually present but abnormal forms will not be seen.
HISTOLOGIC DD : FIBROMATOSIS : more infiltrative & show a fascicular growth pattern also
produces more collagen, less cellular & mitotic figures.
FIBROUS HISTOCYTOMA : More cellular with a storiform pattern, but may
not be as well- circumscribed as Nodular fasciitis.
FIBROSARCOMA: infiltrative and shows a herring-bone pattern, cellular
atypia ( nuclear pleomorphism & hyperchromatism, abundant mitoses.
The spindle cells often show both a myofibroblastic and histiocytic
SMA, MSA, vimentin and CD68 ( KP1) – positivity , Desmin – Negative
Benign Fibrous Histiocytoma
Diverse group of tumors that exhibit both fibroblastic and histiocytic
Cell of origin : still uncertain (may arise from tissue histiocyte, which then
assumes fibroblastic properties )
Other names : Dermatofibroma
Nodular sub-epidermal fibrosis
Common site: skin of the extremities : DERMATOFIBROMA
Oral cavity: rare, if present: Buccal mucosa & vestibule
Frequently affects the older adults.
Appears as painless nodular masses (few mm to cms) that may be ulcerated.
Deeper tumors tend to be larger
Fairly well-demarcated & often circumscribed at the periphery.
Cellular proliferation of spindle shaped fibroblast cells with plump, vesicular nuclei
in storiform pattern (cart wheel or matlike ) with rounded histiocytic-like cells .
Lipid containing xanthoma cells & Tuoton multinucleated giant cells with nuclei
pushed to periphery.
A background of variably dense collagenous tissue & vascularity is seen.
Mixed inflammatory cells present.
Broad group of fibrous proliferations that have a biologic behavior & histopathologic
pattern that is intermediate between those of benign fibrous lesions & Fibrosarcoma.
Show infiltrative, destructive and recurrent growth but no tendency to metastasize.
Superficial Deep ( desmoid)
Familial adenomatous polyposis (FAP) associated
Multicentric (familial )
Intra - Abdominal
H &N region
Presents as firm, painless mass which exhibit rapid growth.
Most frequently occurs in children or young adults : JUVENILE FIBROMATOSIS
Common site : para-mandibular soft tissue region.
Tumor grow to a considerable size, resulting in facial disfigurement.
Destruction of bone seen on radiographs.
Non- encapsulated, poorly circumscribed, infiltrative lesion with a fascicular
growth pattern, usually striated musculature
Cellular proliferation of spindle shaped cells that are arranged in streaming
fascicles & associated with variable amount of collagen.
No atypia, mitotic figures.
Slit like vascular spaces seen
The spindle cells express vimentin, SMA and MSA
Some show desmin expression, β- catenin (adenomatous polyposis coli (APC)
Benign, locally aggressive tumor of fibroblastic origin.
Osseous counter- part of the soft tissue Fibromatosis.
Few cases reported to be associated with tuberous
Patients younger than 30 years of age; no sex predilection.
Sites : mandible (body- ramus) affected more than maxilla.
Slowly progressive, causing swelling of the jaws.
Multilocular or unilocular radiolucency.
Margins –well defined or ill- defined; bone expansion;
thinned out cortex
Consists of interlacing bundles & whorled aggregates of densely collagenous
tissue that contains uniform spindled and elongated fibroblasts
Some areas shows hypercellularity with plump fibroblast nuclei & less collagen.
No cytologic atypia or mitotic figures.
Bone spicules may be present at the interface between the tumor and the
adjacent normal bone; but not an integral part of the lesion.
Interlacing bundles & whorled aggregates of densely collagenous tissue that
contains uniform spindled and elongated fibroblasts
The spindle cells express vimentin and SMA but are
negative for CD34.
Oestrogen receptor positivity may be present and
some show desmin expression.
Malignant tumor of fibroblasts.
Once - most common soft tissue sarcoma.
Most common in the extremities ( femur & tibia ); 10% occur in the H& N region.
Two main types : primary & secondary.
Also reported to arise from pre- existing lesions: fibrous dysplasia, chronic
osteomyelitis, bone infarct, Paget's disease & previously irradiated areas.
Rare soft tissue and bone malignancy of H&N (nasal cavity, paranasal sinus,
When occurs in bone, they may arise from periosteum, endosteum or PDL.
More common in men than in women; fourth decade, also common in
children and young adults (infantile form; good prognosis)
Present as slow- growing masses that may reach considerable size before
they produce pain; secondary ulceration seen as it enlarges.
I. ADULT – TYPE FIBROSARCOMA
a. Myxoid type (myxofibrosarcoma, low grade myxoid MFH)
b. Fibromyxoid type ( low grade fibromyxoid type/ fibromyxoid type with giant
c. Sclerosing epitheliod type
II. JUVENILE/INFANTILE TYPE FIBROSARCOMA.
Uniform fasciculated growth Pattern
fusiform or spindle-shaped cells that vary little in size and shape, have scanty
cytoplasm with indistinct cell borders, and are separated by interwoven collagen
fibers arranged in a parallel fashion.
Mitotic activity varies & Multinucleated giant cells – rarely seen.
Histologic grading of fibrosarcomas is based on the cellularity and
differentiation, mitotic activity, and necrosis
Low-grade (well differentiated) fibrosarcomas are characterized by a uniform, orderly
appearance of the spindle cells associated with abundant collagen
In some cases the cells are oriented in curving or interlacing
fascicles, forming a classic herringbone pattern.
In others, the cells are separated by thick, wire-like collagen
fibers. Secondary features are common.
Low-grade fibrosarcomas may show focal chondro-osseous
Consists of closely packed, less well-oriented tumor cells that are small, ovoid or rounded, and
associated with less collagen.
The fascicular or herringbone growth pattern is less distinct, nuclei - more pleomorphic, mitotic
figures- more numerous, areas of necrosis and/or hemorrhage.
In some fibrosarcomas, scattered cells stain for smooth muscle or muscle-
specific actin, reflecting focal myofibroblastic differentiation.
The lack of cytokeratin immunoreactivity - distinction from monophasic
fibrous synovial sarcoma.
Negative immunostaining for S-100 - distinguishes from spindle cell or
desmoplastic malignant melanomas.
Myxoid type of fibrosarcoma.
Spindle or stellate shaped cells deposited in a myxoid matrix composed of predominantly
of hyaluronic acid. The cells have slightly eosinophilic cytoplasm and indistinct cell borders;
the nuclei are hyperchromatic, are mildly pleomorphic, and have only rare mitotic figures.
1: Nodular fasciitis
3: Nerve sheath Myxoma
4: Spindle cell lipoma
5. Myxoid liposarcoma
6. Extraskeletal myxoid chondrosarcoma
Fibromyxoid type of Fibrosarcoma
Composed of bland spindle-shaped cells with small hyperchromatic oval nuclei, finely clumped chromatin,
and one to several small nucleoli. The cells have indistinct pale eosinophilic cytoplasm and show only mild
nuclear pleomorphism with little mitotic activity. The cells are deposited in a fibrous and myxoid stroma that
tends to vary in different areas of the tumor
Sclerosing epithelioid type of fibrosarcoma
The neoplastic cells are predominantly epithelioid in appearance and are arranged in a
variety of patterns, including nests, cords, strands, and occasionally acini or alveoli.
The cells have oval to round angulated nuclei with finely stippled or vesicular chromatin,
small basophilic nucleoli, and scanty cleared-out or faintly eosinophilic cytoplasm.
Undifferentiated Pleomorphic sarcoma
Once called as Malignant Fibrous Histiocytoma with both fibroblastic & histiocytic
features. (introduced in 1963)
Most common soft tissue neoplasm in late adult life.
Most lesions were later reclassified into other categories- liposarcoma,
leiomyosarcoma, rhabdomyosarcoma, myxofibrosarcoma, melanoma, anaplastic
5 histological variants : storiform- pleomorphic
giant cell (malignant giant cell tumor of soft parts)
inflammatory (xanthosarcoma, malignant xanthogranulomas)
angiomatoid : seen in childhood
Tumor of old age groups.
Men > females
Seen more in extremities & retroperitoneum, rare in H&N regions.
Presents as an expanding mass that may or may not be painful or ulcerated.
Nasal & para nasal sinus tumors : obstructive symptoms.
Irregular nodular lesion, Unencapsulated, attached to surrounding tissues.
Myxoid variant: soft in consistency
Angiomatoid variant : superficially placed than other variants.
Radiographic features: radiolucency with poorly defined margins.
Typically, the lesions are solitary, multilobulated, fleshy masses 5–10 cm in
diameter when first detected.
About two-thirds of these tumors are located in skeletal muscle, <10% are
confined to the subcutis.
A multinodular white mass with areas of hemorrhage and necrosis.
Basic to all MFH - proliferation of pleomorphic spindle shaped cells
showing fibroblastic morphology. Abnormal & frequent mitotic figures,
necrosis & extensive cellular atypia.
Storiform-pleomorphic type, with
a predominantly storiform
The myxoid type is characterized by
myxoid areas in association with cellular
areas indistinguishable from ordinary
The giant cell type of MFH , also termed malignant giant cell tumor of soft parts is a
multinodular tumor composed of a mixture of spindled, rounded, and osteoclast-type giant cells
Inflammatory type of MFH - benign- and malignant-appearing xanthoma cells, the
latter often assuming a gigantic size with bizarre nuclei. Typically, these neoplastic cells
display phagocytosis of neutrophils. The inflammatory component is characteristically
prominent and usually consists of a mixture of acute and chronic inflammatory cells
with marked prominence on the former.
CD68 stain of an
inflammatory MFH with
staining of benign
A myofibroblast is a cell that is in between a
fibroblast and a smooth muscle cell in
Partial smooth muscle
differentiation of a fibroblastic cell
Loss of contractile phenotype of a
smooth muscle cell
differentiation of a progenitor cell
resident in a stromal tissue
Epithelial to mesenchymal
transdifferentiation (EMT) of an
Myofibroblasts are short, bipolar
or tripolar, spindle shaped or
stellate cells with long
containing sparse to moderate
amounts of acidophilic cytoplasm
with indistinct cell margins, and
ovoid, often indented, pale nuclei
containing a small nucleolus. They
have contractile elements and
synthesize collagen, fibronectin,
Myofibroma/ myofibomatosis are benign tumours of myofibroblasts which are
solitary or multicentric, respectively.
These tumours show a predilection for the head and neck, with a particular
propensity for arising in and around the oral cavity
More commonly described in childhood
Rare neoplasms with predilection for H& N region.
Most frequently in the first 4 decades of life (mean age:22 yrs)
Site : mandible, tongue & buccal mucosa.
Presents as painless mass that show rapid enlargement.
Radiographs: radiolucent defects that are poorly defined, sometimes well-
defined & multilocular.
Multicentric myofibromatosis : affects neonates & infants who have tumors of
the skin, sub-cutaneous tissue, muscle, bone & viscera.
Number of tumors may vary from several to more than 100.
Interlacing bundles of spindle cells with tapered or blunt ended nuclei and
Nodular fascicles may alternate with more cellular zones- giving a biphasic
Centrally, the lesion is more vascular with hemangiopericytoma like appearance.
Positive for SMA, MSA and negativity for DESMIN which rules out
Leiomyoma & Leiomyosarcoma
INFLAMMATORY MYOFIBROBLASTIC TUMOR
Intermediate type of neoplasm consisting of variable numbers of inflammatory
cells and myofibroblastic spindle cells.
Rare outside the lung, liver and orbit.
Liston et al. in 1981 was the first to report IMTs of oral cavity in three children.
Seen in the sinonasal tract, larynx, oral cavity and salivary glands.
Other names : Inflammatory pseudotumor (IPT)
plasma cell granuloma,
Spindle cell pseudotumor
Three main patterns:
monomorphic spindle cells arranged in fascicles
myxoid, nodular fasciitis-like areas
hypocellular, hyalinized areas
A variable infiltrate of inflammatory cells associated with the tumour cells
Spindle shaped cells with fasciculated architecture, hypocellular
fibrous areas with numerous plasma cells, and concurrent
ANAPLASTIC LYMPHOMA KINASE-1 (ALK-1) - 35 TO 60 % POSITIVE
LOW GRADE MYOFIBROSARCOMA
Malignant tumour of Myofibroblasts.
Indolent neoplasms but can recur and metastasize after a long period.
Usually affects adults and is uncommon in children.
Intra oral tumors- usually slows growing & asymptomatic.
Oral cavity-the tonsil, mandible, maxilla
Usually affects deep soft tissue sites and is more often poorly
circumscribed with fascicles and individual cells infiltrating between
muscle fibers, although focal circumscription is not unusual.
The lack of significant atypia confuses with benign diagnosis such as
nodular fascitis, proliferative myositis, and Fibromatosis.
A population of spindle-shaped cells showing vesicular nuclei with fine
stippled chromatin and a small nucleolus. The cytoplasm was pale and
eosinophilic with indistinct margins.
The cells will be arranged in variably orientated short fascicles or
vaguely storiform whorls , extending between individual skeletal muscle
A mild degree of nuclear pleomorphism, anisonucleosis, and
hyperchromatism will be seen.
A moderate amount of collagen was present in several foci, but a myxoid
or hyalinized stroma can also be seen.
Occasional lymphocytes, plasma cells, and mast cells.
Benign tumors of smooth muscle that most commonly occur in the uterus, GIT
Uncommon in the oral cavity probably because of the general absence of
smooth muscle except in the blood vessel walls and occasionally in the
circumvallate papillae of the tongue.
Vascular leiomyoma (angiomyoma / angioleiomyoma )
Presents as slow growing, firm mucosal nodule; asymptomatic,
sometimes painful, 1-2 cm in diameter.
Symptoms : sore throat or tumor in the throat
Can occur at any age.
Solid leiomyoma normal colour
Angio leiomyoma bluish hue
Sites: tongue, lips, palate & cheek.
Intra-osseous cases – unilocular radiolucencies
Well circumscribed tumors that consists of interlacing bundles of spindle
shaped smooth muscle cells.
The nuclei are elongated, pale staining & blunt ended (cigar shaped)
Angio-leiomyoma multiple tortuous blood vessels with thickened walls
caused by hyperplasia of their smooth muscle coats.
Interwining bundles of smooth muscle may be found between the vessels
Masson trichrome: to differentiate
between collagen & smooth
Muscle: BRIGHT RED
Malignant neoplasm of smooth muscle differentiation.
Account for 5 - 10% of all soft tissue sarcoma.
Common sites: uterine wall & GIT; Oral cavity – Rare.
Develops either through malignant transformation of leiomyoma or de novo.
Middle aged & older adults.
Site : jaw bones, cheek & floor of the mouth.
Appears as an enlarging, lobulated mass that may or may not be painful;
Fascicles of spindle shaped cells with abundant eosinophilic cytoplasm and blunt
ended, cigar shaped nuclei.
Some tumors : rounded epitheliod cells with eosinophilic / Clear cytoplasm.
Degree of pleomorphism varies.
More than 5 or more mitosis per 10 high power field : MALIGNANT.
PAS: POSITIVE (GLYCOGEN) & MASSON TRICHROME: CELL CYTOPLASM – BRIGHT RED
MSA (HHF 35)
Benign neoplasm of skeletal muscle.
Introduced by Zenker (1864).
CARDIAC EXTRA- CARDIAC
1. ADULT TYPE
2. FETAL TYPE
3. GENITAL TYPE
Clinical features – Adult Rhabdomyoma
Middle aged & older adults; 70 % occurs in men.
Sites : pharynx, oral cavity, larynx
Oral cavity – floor of the mouth, soft palate, base of the tongue.
The tumor appears as a nodule or mass that grows to many centimeters;
sometimes multinodular in nature.
Young children; male predilection
Site : face &peri-auricular region, nasopharynx, but not in mouth.
Clinical features – fetal Rhabdomyoma
Two related types: MYXOID TYPE AND INTERMEDIATE TYPE
The myxoid type - primitive oval or spindle-shaped cells with indistinct cytoplasm,
interspersed immature skeletal muscle fibers reminiscent of fetal myotubes seen
during the seventh to tenth weeks of intrauterine life, and a richly myxoid matrix.
Histopathology- Fetal Rhabdomyoma
MSA (HHF 35)
The intermediate type - characterized by the presence of numerous differentiated
muscle fibers, less conspicuous or absent spindle-shaped mesenchymal cells, and
little or no myxoid stroma.
The predominant cells are broad, strap-shaped muscle cells with abundant
eosinophilic cytoplasm, centrally located vesicular nuclei, and frequent cross-
striations reminiscent of the cells seen in adult rhabdomyomas; many of the cells
contain glycogen and are often vacuolated
Histopathology- Fetal Rhabdomyoma
Malignant neoplasm of skeletal muscle differentiation.
More common in young children; 60% of soft tissue sarcomas in childhood.
Only 2-5 % of soft tissue sarcomas in adults.
35 % of cases – H & N; Genitourinary tract – 2nd most common site.
Occurs during the first decade of life.
Embryonal type – most common in the first 10 years of life. (60%)
Alveolar type – between 10-25 years.(20-30%) H& N
Pleomorphic type - < 5 % cases extremities
NATIONAL CANCER INSTITUTE
Embryonal rhabdomyosarcoma, spindle cell type
In 1992, Cavazzana et al. reported 21 ER composed predominantly (>80%) of
elongated spindle cells.
Rare variant; 3 % of all RMS
Male predilection; paratesticular location (38%) followed by H & N(27%)
The tumor is composed almost exclusively of elongated fusiform cells with
cigar-shaped nuclei and prominent nucleoli.
The tumor cells have eosinophilic fibrillar cytoplasm with distinct cellular
borders, closely resembling late-stage fetal myoblasts.
Cytoplasmic cross-striations may be observed.
The collagen-rich form is characterized by spindle cells separated by abundant
collagen fibers arranged in a storiform or whorled growth pattern.
The collagen-poor form is a more cellular proliferation of cells arranged in
bundles or fascicles, reminiscent of leiomyosarcoma.
Palisaded encapsulated neuroma
Benign neural tumor with distinctive clinical & histopathological features.
Represents one of the common superficial nerve tumors.
Cause – uncertain ; trauma.
Generally considered to be a reactive lesion rather than neoplasm.
Striking predilection for the face; 90% of the cases.
Nose & cheek – most common sites; oral cavity – hard palate & maxillary labial mucosa
5- 7th decade of life.
Smooth surfaced, painless, dome shaped papule or nodule (< 1cm)
Well – circumscribed & encapsulated tumor.
Tumor consists of moderately cellular interlacing fascicles of spindle cells
that are consistent with Schwann cells.
Nuclei – wavy & pointed; palisaded; no pleomorphism or mitotic activity.
S -100 POSITIVE
Benign neoplasm that is derived from the proliferation of Schwann cells of the
neurilemma or nerve sheath.
25- 48 % occur in H &N.
Bilateral neurilemomas of the auditory- vestibular nerve-
NEUROFIBROMATOSIS TYPE II
Slow growing, encapsulated tumor.
As it grows, it pushed the nerve aside.
Asymptomatic mass; pain & tender occur sometimes.
Young & middle aged adults; few mm to several cms.
Tongue – common site, centrally within the bone; bone expansion.
Intra – osseous : posterior mandible; unilocular / multi-locular radiolucencies.
Encapsulated tumor that shows two microscopic patterns in varying amounts:
ANTONI A – streaming fascicles of spindle shaped Schwann cells.
cells form a palisaded arrangement around central, acellular, eosinophilic
areas: VERUCAY BODIES (reduplicated basement membrane & cytoplasmic processes)
ANTONI B - less cellular & less organized
spindle cells are randomly arranged within a loose myxomatous stroma.
Degenerative changes can be seen in some older tumors : ANCIENT NEURILEMMOMAS.
Changes - hemorrhage, hemosiderin deposits, inflammation, fibrosis & nuclear atypia
Ancient schwannoma with cyst formation and interstitial
Neuroblastoma-like schwannoma composed of rounded Schwann cells
forming rosettes (A). Other areas had a more conventional appearance
Cellular schwannoma with long fascicles of Schwann cells
without Antoni B areas or Verocay bodies
involving the dermis
Epithelioid schwannoma. Note the cohesive nests of
bland epithelioid cells S- 100
Most common type of peripheral nerve neoplasm.
Arises from a mixture of cell types; schwann cells & perineural fibroblasts.
Appear as solitary or multiple lesions as part of the syndrome: NEUROFIBROMATOSIS
Appears as slow growing, soft painless lesions that vary in size from small nodules to
Site : skin; oral cavity – tongue & buccal mucosa; centrally within the bone.
Well demarcated or poorly defined unilocular or multilocular radiolucency.
THREE GROWTH PATTERNS : Localized, Diffuse, Or Plexiform NF 1
Interlacing bundles of elongated cells with wavy, darkly-stained nuclei.
The cells are intimately associated with wire-like strands of collagen that have
been likened to “shredded carrots.”
Small to moderate amounts of mucoid material separate the cells and collagen.
The stroma of the tumor - mast cells, lymphocytes, and rarely xanthoma cells.
Less frequently, the neurofibroma is highly cellular and consists of Schwann cells
set in a uniform collagen matrix devoid of mucosubstances.
Always develop during early childhood, often before the cutaneous
neurofibromas have fully developed.
Involve an entire extremity give rise to the condition known as elephantiasis
neuromatosa, in which the extremity is enlarged.
The overlying skin is loose, redundant, and hyperpigmented, and the
underlying bone may be hypertrophied.
Macroscopically, plexiform neurofibromas are large lesions that affect large
segments of a nerve, distorting it and contorting it into a “bag of worms”
The lesion consists of a tortuous mass of expanded nerve branches, which are
seen cut in various planes of section.
In the early stages the nerves may simply have an increase in the endoneurial
matrix material, resulting in wide separation of the small nerve fascicles.
With continued growth the cells spill out of the nerves into soft tissue, creating
a diffuse variant of neurofibromatous tissue such that NF1 lesions can have
both plexiform and diffuse areas.
Unlike localized neurofibromas, they may display nuclear atypia. Because these
lesions are at greatest risk to undergo malignant transformation
Malignant peripheral nerve sheath tumor
Malignancy of peripheral nerve origin.
5 % of all soft tissue tumors.
50% occur in patients with NF1.
Common sites : proximal portions of the extremities & trunk.
Oral cavity : mandible, lips & buccal mucosa.
10 -15% - H & N.
Young adults; NF -1 associated younger than the non associated.
Enlarging mass showing rapid growth with associated pain.
Fascicles of atypical spindle shaped cells.
More irregular in shape with wavy or comma shaped nuclei.
In addition to streaming fascicles, less cellular myxoid areas are also present.
Some tumors show skeletal muscle differentiation (malignant triton tumor),
cartilage, bone or glandular structures.
Spindle cell Lipoma
Originally described as a distinct entity by Enzinger and Harvey in 1975.
Usually arises in men; 45-60 years of age.
Subcutaneous tissue of the posterior neck, shoulder, and back; oral cavity- rare.
Slow growing, typically solitary, circumscribed or encapsulated, painless, firm
nodule, usually centered in the subcutaneous tissue
Vary widely in its appearance.
Some tumors are predominantly composed of mature adipose tissue with
only scattered spindle cell or pleomorphic elements.
Other tumors are predominantly solid and lack any significant lipomatous
The classic spindle cell lipoma consists
of a relative equal mixture of mature
fat and spindle cells.
The spindle cells are uniform with a
single elongated nucleus and narrow,
bipolar cytoplasmic processes .
The cells may be haphazardly
distributed but tend to be arranged in
short, parallel bundles.
IHC- the spindle cells in spindle cell
lipoma are consistently positive for
Spindle Cell Liposarcoma
A very rare and unusual form of liposarcoma consisting almost entirely of loosely
arranged fibroblast-like spindle cells oriented along a single plane and surrounded
by a delicate reticulin meshwork.
At low power, the lesion bears a superficial similarity to spindle cell lipoma,
although it is far more cellular.
Spindle cell hemangioma
First described in 1986 as “spindle cell Hemangioendothelioma”; an acral
vascular tumor characterized by cavernous blood vessels and spindled areas
reminiscent of Kaposi sarcoma.
Young adults ;subcutis of the distal extremities, particularly the hand.
Occasionally associated with Maffucci syndrome, Klippel-Trénaunay syndrome.
Most begin as a solitary nodule but have a remarkable tendency to give rise to
multiple lesions in the same general area.
The lesions are composed of thin-walled cavernous vessels lined by flattened endothelial
cells and containing a mixture of erythrocytes and thrombi.
Between the cavernous spaces are bland spindled areas reminiscent of Kaposi sarcoma.
Hemangiopericytoma - Solitary Fibrous Tumor
First coined by Stout and Murray for tumors thought to originate from the
pericytes, a modified dendritic-like smooth muscle cell encircling blood vessels.
In 1976, by Enzinger and Smith emphasized the staghorn, partially hyalinized
vessels surrounded by small rounded and fusiform cells.
Hemangiopericytoma also coincided with the increasing popularity of the
diagnosis of solitary fibrous tumor (SFT), a pleural-based lesion first described
by Klemperer and Rabin.
Had many overlapping features with classic hemangiopericytoma: CD34
immunoreactivity, paved the way for the popular belief that all
hemangiopericytomas were, or should become, solitary fibrous tumors.
Slow growing, mucosal, painless or deep soft tissue mass
Buccal mucosa – 75%; adults & rare in children.
Nasal cavity & paranasal sinuses with the symptoms of nasal obstruction &
Well circumscribed lesions with variable microscopic appearance.
The cellular end of this spectrum corresponds to “classic hemangiopericytoma”
and the hyalinized end to “classic solitary fibrous tumor.”
Many cases have hybrid features.
Classic hemangiopericytoma consists of tightly packed round to fusiform cells
with indistinct cytoplasmic borders which are arranged around an elaborate
As a rule, the dilated, branching vessels divide and communicate with small or
minute vessels which may be partly compressed and obscured by the
surrounding cellular proliferation.
Typically, the dividing sinusoidal vessels have a “staghorn” or “antler-like”
In contrast, lesions having features of classic “solitary fibrous tumor” consist
principally of spindle cells.
The arrangement of the cells varies from area to area in the same tumor.
In some zones the cells are arranged in short, ill-defined fascicles, whereas in
others they are arranged randomly in what has been described as a
Staghorn vessels, occasionally present, are not as striking as in classic
Rare malignancy of vascular endothelium which may arise from
either blood or lymphatic vessel.
More than 50% - occur in H&N (scalp & forehead)
Oral lesions- rare
Older adult patients
Early lesions – bruise – delay in diagnosis; lesion continues to
enlarge resulting in elevated, nodular or ulcerated surface.
Vary from well-differentiated neoplasms with vascular channels lined by
atypical endothelial cells with few mitoses to poorly differentiated
neoplasms composed of solid sheets of epithelioid or spindle cells
exhibiting brisk mitotic activity.
Poorly defined vascular spaces, multilayered endothelial lining, and
papillary projections into the vascular lumen may also be observed.
Hemorrhage, necrosis, and lymphocytic infiltration are common
One hallmark of poorly differentiated angiosarcoma - presence of
fragmented erythrocytes in the intracytoplasmic vacuoles
Unusual vascular neoplasm that was described by Moritz Kaposi in 1872.
Caused by HHV-8; more associated with HIV patients.
Arises from endothelial cells; lymphatic origin.
4 CLINICAL PRESENTATION:
Endemic (African )
Iatrogenic immunosuppression associated
The Earliest (patch) stage – a flat lesion characterized by a proliferation of miniature
vessels surrounding larger ectatic vessels
Plaque stage produces slight
elevation of the skin.
The vascular proliferation
usually involves most of the
dermis and may extend to the
A discernible but relatively
bland spindle cell component,
initially centered around the
channels, appears at this
In time, the spindle cell foci
coalesce and produce the
classic Nodular lesions of
Osteosarcoma – malignancy of mesenchymal cells that have the ability to
produce osteoid or immature bone.
Variants : osteoblastic, chondroblastic, fibroblastic
Minimal amount of osseous matrix with or without cartilage.
Overall histological appearance is similar to fibrosarcoma or undifferentiated
pleomorphic sarcoma (malignant fibrohistiocytic tumour)
Synovial sarcoma is a clinically and morphologically well-defined entity that,
despite its name, is extremely uncommon in joint cavities and is encountered
in areas with no apparent relation to synovial structures.
It occurs primarily in the para-articular regions of the extremities, usually in
close association with tendon sheaths, bursae, and joint capsules.
Teenagers & young adults.
Gradual enlarging mass associated with pain
H &N region- paravertebral & parapharyngeal region.
Oral cavity – tongue & cheek.
Two major categories of synovial sarcoma: biphasic and monophasic types.
biphasic type, with distinct epithelial and spindle cell components in varying
monophasic fibrous type
rare monophasic epithelial type
poorly differentiated (round cell) type.
Odontogenic Fibroma (OF)
Tumors of odontogenic ectomesenchyme.
Simple type: An expansile, non infiltrating connective tissue lesion
resembling a dental follicle
It is relatively acellular, the fibers being quite delicate, and there is a
considerable amount of ground substance yielding a fibromyxoid quality.
It may exhibit inactive-looking rests of odontogenic epithelium but they
are seldom numerous.
WHO type: cellular connective tissue.
It often occurs in fibroblastic strands that are interwoven with less cellular
areas in which numerous small blood vessels are present
Foci of calcified collagenous matrix, resembling dysplastic cementum,
osteoid atubular dysplastic dentin
Islands or strands of inactive-looking odontogenic epithelium are an
▸A myxoid tumour which is largely confined to the tooth-bearing areas
of the jaws
▸Odontogenic myxomas are locally aggressive, non-encapsulated, non-
metastasizing neoplasms that infiltrate bone marrow spaces.
▸Cut sections characteristically reveal a white-gray color in the mucoid
substance, which will stick to an instrument when touched.
Loose, abundant mucoid stroma that contains rounded, spindle-shaped, or
Cellular and nuclear pleomorphism is rare, as is mitotic activity
Usually tumor cells are evenly spaced with in a fine fibrillar mucinous matrix
The stroma may be relatively avascular or may exhibit delicate capillaries
Occasional positivity to S-100 protein
and muscle specific actin
Myoepithelium -rich pleomorphic adenoma comprise a spectrum of benign myoepithelial
tumor with overlapping histologic features and similar clinical behavior and arise almost
exclusively in the normally or ectopically situated salivary glands.
First used by Sheldon in 1943.
Sites: parotid, palate
< 1% of all major & minor salivary gland tumors.
Composed exclusively of neoplastic myoepithelial cells.
Predominantly spindle shaped cells or plasmacytoid.
Epitheliod and clear cells are also present.
Single cell type or combination of cell types predominates.
Does not contain the chondromyxoid stroma of PA.
ELLIS GL (1991) defined it as a malignant epithelial neoplasm whose tumor cells
demonstrate cytologic differentiation towards myoepithelial cells and lack ductal or acinar
Intermediate to high grade carcinoma
Patient complaints of a painless mass.
General morphologic features resemble tumor cells in myoepithelioma.
Tumor cells are spindle shaped or plasmacytoid; they will be intermixed or one
cell type predominates.
Quite cellular ; suggestive sarcoma rather than carcinoma
Stroma in other parts of the tumor may be conspicuous & myxoid.
Distinguished from other benign tumors by their infiltrative & destructive
growth; increased mitotic activity & pleomorphism
IHC: CYTOKERATIN, S100, SMA, GFAP.
Diagnosis of Spindle cell Neoplasm
Algorithm for mucosal malignant tumors
If in situ component, dysplasia, squamoid traits If absent –IHC to be done
Spindle Cell Carcinoma
HMB45, melan A
SMA strongly and
CK, EMA, AE1/AE3,
CD - 34
confirm with H-
FLI-1 –specific for
Spindle cell lesions of head & neck are diverse & diagnostically challenging
High index of suspicion of spindle cell carcinoma for any malignant tumor
with spindle cells
Clinical correlation is valuable.
PATHOLOGISTS SHOULD TAKE PARTICULAR CARE BEFORE RENDERING FINAL
RULE OF THUMB –IN ADULTS MALIGNANT SPINDLE CELL ARE MORE LIKELY
TO REPRESENT CA OR MELANOMA THAN A TRUE SA
Defined as a schwannoma composed predominantly or exclusively of Antoni A areas that lack Verocay bodies
A characteristic, but not specific feature of the well-established lesion is the presence of the hyaline globule. These periodic acid-Schiff (PAS)-positive, diastase-resistant spherules may be located both intracellularly and extracellularly.