21 

Benign Neoplasms of the Neck (Soft

Tissue, Bone, and Lymph Node)
■  Diana Bell

■  LYMPHANGIOMA (CYSTIC HYGROMA)

LYMPHANGIOMA (CYSTIC HYGROMA)—DISEASE
FACT SHEET
Lymphangiomas are rare congenital lymphatic malforma-
tions, with up to 70% reported in the head and neck. Definition
They are separated into three types: capillary, cavernous, ■ A benign cystic neoplasm composed of dilated lymph vessels

and cystic (cystic hygroma). Lymphangiomas comprise

Incidence and Location
approximately 25% of all vascular neoplasms in children
■ Represents 25% of congenital cervical cysts
and adolescents; approximately 25% of cervical cysts ■ Up to 70% of lymphangiomas occur in the head and neck
are lymphangiomas.
Morbidity and Mortality
■ Mortality 3%-7% (via pressure destruction of adjacent vital

structures)
CLINICAL FEATURES
Sex and Age Distribution
■ No significant sex difference
Approximately two-thirds of lymphangiomas are noted
■ Most present shortly after birth and 95% by the second year
shortly after birth, and 95% are present by the end
of the second year of life. Cystic hygroma may also be Clinical Features
detected in utero with ultrasonography. Cystic hygroma ■ Slowly enlarging painless mass
may be associated with fetal hydrops and several genetic ■ May produce pressure symptoms owing to its size

abnormalities, most notably Turner syndrome (Fig. ■ Associated with fetal hydrops and Turner syndrome

21.1) but also Noonan syndrome and trisomies 13, 18,

and 21. In general, symptoms are related to pressure Prognosis and Treatment
■ May become secondarily infected
caused by the slowly enlarging mass or extension of
■ Surgery is the treatment of choice; sclerosing agents and laser
the mass into the posterior neck or, less commonly,
can be used
into the anterior compartment, cheek, mediastinum, ■ Up to 50% recurrence depending on size and site of lesion
or axilla. When the hygroma is located superior to the (due to incomplete excision)
hyoid bone, it may cause dysphagia or airway compres-
sion. Ultrasound will show a cystic lesion, frequently
identified prenatally, while computed tomography
(CT) studies will show a nonenhancing multilocular
cystic mass.
PATHOLOGIC FEATURES
Cavernous lymphangioma forms an ill-defined, spongy,
compressible mass and is found most commonly in the
tongue, cheek, floor of mouth, and lips; it is uncommon Cystic lymphangiomas (hygromas) vary from a single
in the soft tissues. In contrast, capillary lymphangioma soft mass with a pseudocontour to lobulated multicystic
is usually confined to the skin and is clinically the least masses (Fig. 21.1). They contain clear to white-turbid
significant of the three types. fluid, described as milk-like (Fig. 21.1). Histologically,
509
510 HEAD AND NECK PATHOLOGY

A B

C
FIGURE 21.1
(A) Bilateral cystic masses are noted in
the posterior neck of this fetus, affected
with Turner syndrome. (B) Turbid-milky
fluid removed during a fine needle
aspiration of a large posterior neck cyst
in a child (lymphangioma). (C) A
translucent mass, showing delicate
vessels in the wall of a lymphangioma,
filled with clear-watery fluid.

A B

FIGURE 21.2
(A) Cystic lymphangioma showing dilated lymphatic spaces. (B) Lymphocytes are noted within the proteinaceous fluid.

they consist of dilated, thin-walled spaces filled with

ANCILLARY STUDIES
eosinophilic, proteinaceous fluid and lined by flat endo-
thelial cells (Fig. 21.2). The intervening stroma contains
scattered lymphoid aggregates and wisps of smooth muscle Endothelial markers (factor VIII–related antigen [FVIII-
fibers (Fig. 21.3). Fibrosis may be increased in lesions RAg], CD31, CD34, and Ulex europaeus) can be expressed
that have been present for a long time. by endothelial cells in both hemangiomas and
CHAPTER 21  Benign Neoplasms of the Neck (Soft Tissue, Bone, and Lymph Node) 511

A B

C D

FIGURE 21.3
(A) Lymphatic spaces subtended by smooth muscle. (B) Lymphoid cells and proteinaceous fluid. (C) Lymphoid elements with fibrosis surrounding fluid-filled
spaces. (D) Flat, attenuated endothelial cells line the cavity.

lymphangiomas. D2-40 (podoplanin) may be a lymphatic-

specific marker, along with CD9 and lymphatic vessel LYMPHANGIOMA (CYSTIC HYGROMA)—
PATHOLOGIC FEATURES
endothelial receptor 1 (LYVE-1), although podoplanin
may be easier to interpret. Gross Findings
■ Sponge-like cystic mass

Microscopic Findings
DIFFERENTIAL DIAGNOSIS
■ Dilated, thin-walled spaces filled with proteinaceous fluid

■ Lined by flat endothelial cells

■ Lymphoid aggregates in stroma
The most common differential diagnosis is with cavernous
■ Wisps of smooth muscle in the wall
hemangioma. Lymphangioma contains proteinaceous
fluid and the surrounding tissues are usually infiltrated Immunohistochemical Findings
by lymphocytes, whereas cavernous hemangiomas are filled ■ Positive with factor VIII–related antigen, CD31, CD34, Ulex
with red blood cells and lack valve structures. Metastatic europaeus
papillary thyroid carcinoma may have flattened cells along ■ D2-40 (podoplanin) may be specific lymphatic marker (also

the spaces, but TTF1 and/or thyroglobulin will be positive. CD9 and LYVE-1, although less common)
Furthermore, a lymph node architecture should be rec-
Pathologic Differential Diagnosis
ognizable, often at the periphery.
■ Cavernous hemangioma, metastatic papillary thyroid carcinoma

PROGNOSIS AND THERAPY

Mortality rates are between 3% and 7%, specifically treatment or injected sclerosing agents (such as bleomycin)
related to pressure destruction of vital structures of the are alternative therapies. Recurrence rates range from
neck. Lymphangiomas may occasionally become infected 15% to 50% and are highest when the lymphangioma
and may cause difficulty swallowing or respiratory dis- is incompletely removed. Malignant transformation is
tress. Surgery is the treatment of choice, while laser not documented.
512 HEAD AND NECK PATHOLOGY

planning may yield a better outcome. CT or magnetic

■  TERATOMA
resonance imaging (MRI) usually shows a multilocular
mass (Fig. 21.4). Cervical teratomas in adults are extremely
Teratomas are neoplasms composed of elements from rare, with patients reporting a rapidly enlarging neck
each of the three germ cell layers (ectoderm, endoderm, mass.
and mesoderm). About 1 in 4000 live births have a tera-
toma, with approximately 2% involving the head and
neck, most commonly the neck, oropharynx, nasopharynx,
and orbit. Specifically, cervical teratomas represent less
TERATOMA—DISEASE FACT SHEET
than 3% of all teratomas and less than 1% of all neck
masses in children. Teratomas are separated, histologically, Definition
into mature or immature, solid or cystic, and are classified ■ Neoplasm composed of mature or immature elements from

as benign or malignant depending on the degree of tissue ectoderm, endoderm, and mesoderm
maturation. In general, teratomas of the neck in neonates
or infants are clinically benign, although they may be Incidence and Location
■ Cervical teratomas represent 3% of all teratomas
histologically mature or immature. By comparison, tera-
■ Less than 1% of pediatric neck masses
tomas in adults are more likely to be clinically malignant
and histologically immature.
Morbidity and Mortality
■ High morbidity but low mortality in neonates and infants

■ High mortality in older children and adults

CLINICAL FEATURES
Sex and Age Distribution
■ Equal sex distribution

■ More than 90% occur in neonates or infants

More than 90% of cervical teratomas occur in neonates
or infants and are rare in patients older than 1 year.
Clinical Features
They occur with similar frequency in boys and girls. In
■ Neck mass
addition to a neck mass, severe respiratory distress is ■ Respiratory distress
notable in neonates, frequently leading to airway com- ■ Frequent association with congenital malformations

promise and requiring immediate surgery. Polyhydramnios ■ Polyhydramnios seen in 20% of neonatal lesions

and other malformations may be seen in approximately

20% of patients, many of whom will show an elevated Prognosis and Treatment
α-fetoprotein concentration in amniotic fluid. Failure of ■ Prognosis is very good in neonates and infants but guarded in

older children and adults

midline structure development may result in fetal demise, ■ Surgery
even though the lesion is histologically benign. If detected
prenatally by ultrasonographic examination, surgical

A B

FIGURE 21.4
Magnetic resonance imaging demon-
strates a large mass involving the
oropharynx, nasopharynx, and neck. (A)
Axial T2-weighted image. (B) Coronal
T1-weighted image.
CHAPTER 21  Benign Neoplasms of the Neck (Soft Tissue, Bone, and Lymph Node) 513

mesoderm (Fig. 21.5). The most common finding is neural

PATHOLOGIC FEATURES tissue arranged in islands, tubules, and rosette-like forma-
tions of immature neuroepithelium or mature glial tissue
GROSS FINDINGS (Fig. 21.6), including retinal anlage epithelium (Fig. 21.7).
A variety of epithelia are seen, including squamous,
Grossly, the tumors are encapsulated, lobulated, and respiratory, and enteric-type mucosa, with solid organ
usually cystic, but they can be solid or multiloculated. tissues occasionally noted (pancreas, liver, thyroid; Fig.
They measure up to 12 cm in greatest diameter. 21.7). The epithelium may line a cyst, with sebaceous
units and hair frequently identified. Nodules of cartilage,
MICROSCOPIC FINDINGS fat, and muscle blend with the surrounding epithelial or
glial tissues. The tissue may be mature or immature
Histologically, the tumors are composed of an assem- (embryonic), with the volume of immature tissues
blage of mature or immature tissues from the three determining the overall grade of the tumor. The designa-
embryonic germ cell layers: ectoderm, endoderm, tion benign mature is used for tumors containing only

FIGURE 21.5
This benign, mature teratoma contains a
primitive esophagus adjacent to a primitive
trachea. Elements from other germ cell
layers were noted elsewhere.

A B

FIGURE 21.6
(A) Teratoma containing neuroglial tissue with focal fibrosis. (B) Adjacent focus showing ependymal and choroid plexus elements.
514 HEAD AND NECK PATHOLOGY

A B

C D

FIGURE 21.7
(A) Retinal anlage epithelium. (B) Mature cartilage adjacent to pancreatic tissue. (C) Thyroid parenchyma with immature fat. (D) A rosette of immature glial
tissue.

yolk sac tumor, embryonal carcinoma, or choriocarci-

TERATOMA—PATHOLOGIC FEATURES noma), while uncommon, automatically place the tumor
in the malignant category.
Gross Findings
■ Cystic, solid, or multilocular lobulated mass

Microscopic Findings
■ Mature or immature tissues from all germ cell layers
ANCILLARY STUDIES
■ Squamous, respiratory, glandular, and cuboidal epithelium

■ Organ differentiation may be seen

■ Neural tissues, including glial elements, choroid plexus, immature
Immunohistochemical stains with α-fetoprotein and
neuroblastema, and pigmented retinal anlage
■ Bone, cartilage, muscle, and fat
human chorionic gonadotropin may be of help in finding
islands of yolk sac tumor or choriocarcinoma, respectively,
Immunohistochemical Findings in malignant teratomas. However, immunohistochemistry
■ α-fetoprotein and human chorionic gonadotropin if yolk sac is generally not necessary for diagnosis.
tumor or choriocarcinoma are present (respectively)

Pathologic Differential Diagnosis

■ Hamartoma, neuroblastoma, malignant germ cell tumors,

metastatic testicular teratoma DIFFERENTIAL DIAGNOSIS

A broad differential diagnosis exists with these hetero-

geneous tumors when initially evaluated on small biopsy
mature elements; benign immature is used if there are samples, offering limited sampling. Hamartoma, choris-
foci of immature elements within a tumor that has a toma, ectopia, encephalocele, neuroblastoma, rhabdomyo-
majority of mature elements; and malignant is used if sarcoma, and malignant germ cell tumors may all be
the majority of the tumor is composed of immature considered in the differential. However, attention to the
elements. Foci of malignant germ cell tumor (such as nondescript mesenchymal background and heterogeneity
CHAPTER 21  Benign Neoplasms of the Neck (Soft Tissue, Bone, and Lymph Node) 515

of elements, including embryonic forms, provides a clue

to the diagnosis. A hamartoma is readily ruled out by ECTOPIC HAMARTOMATOUS THYMOMA—DISEASE
the presence of tissues that are not indigenous to the FACT SHEET
location and/or that have an immature appearance.
Definition
Depending on the patient’s age, cervical metastasis from ■ Subcutaneous tumor composed of bland spindle cells, nests of
a gonadal teratoma should also be considered in the epithelioid cells, and adipocytes
differential diagnosis.
Incidence and Location
■ Rare neoplasm

■ Low neck and supraclaficular/suprasternal notch region

PROGNOSIS AND THERAPY Sex and Age Distribution

■ Male predominance (M : F 3.4 : 1)

■ Peak incidence in the 5th decade

The prognosis of cervical teratoma in newborns and
infants is excellent, although teratomas of the neck, despite Clinical Features
their favorable histology, may cause significant morbidity ■ Slow-growing, well-circumscribed swelling/mass in the lower

owing to their important location. Tracheotomy or oral neck or supraclavicular region

intubation may be required, along with a nasogastric
tube for feeding. Death does occur as a result of associated Prognosis and Treatment
■ Benign clinical course
developmental malformations of the vital structures of
■ No recurrence after local excision
the neck. Therefore, surgery should be instituted without ■ Rare malignant transformation
delay because the preoperative mortality is significant.
Many advocate delivering a fetus by an ex utero intra-
partum treatment (EXIT) procedure to yield the best
possible outcome. In adults, in whom a malignant histol-
ogy is more common, the biologic behavior of the tumors
is more aggressive, with a poorer clinical outcome, as
expected. Metastasis to lymph nodes and lung is common.
Surgery with adjuvant chemotherapy and radiation is
advocated, although often with mixed results.

■  ECTOPIC HAMARTOMATOUS THYMOMA

Ectopic hamartomatous thymoma (EHT) is a rare benign

neoplasm characteristically composed of a mixture of
spindle cells, epithelial cells, mature adipose tissue, and
lymphocytes. It is thought to arise from misplaced deriva-
tives of the branchial pouch (remnant of cervical sinus of
His). There is no evidence that the tumor is related to the
thymus; some studies suggest that it originates from the FIGURE 21.8
salivary gland. Alternate terminology includes branchial The cut surface of the mass shows gray-white, solid tumor with scattered,
anlage mixed tumor and biphenotypic branchioma. small cystic spaces and yellow foci of adipose tissue. (From Seok SH, Lee
DH, Kang SH, Bae YK. Ectopic hamartomatous thymoma- a case report along
with a review of the literature concerning the histogenesis and new nomen-
clature. Korean J Pathol. 2006;40:292–296.)

CLINICAL FEATURES PATHOLOGICAL FEATURES

EHT occurs in the soft tissue of lower neck/supraclavicular, GROSS FINDINGS

suprasternal, and presternal regions, and most patients
are men, who present at a mean age of 46 years. It is EHT is usually a well-circumscribed mass, measuring
usually seen as a slow-growing, well-circumscribed mass. up to 5 cm. These tumors have a rubbery consistency
It does not affect the thyroid gland, the larger vessels of and a gray-white to tan cut surface. Cyst formation can
the neck, or the mediastinum. be seen (Fig. 21.8).
516 HEAD AND NECK PATHOLOGY

MICROSCOPIC FINDINGS or clear cell differentiation (Figs. 21.10 and 21.11; see
also Fig. 21.9). Occasionally, focal smooth muscle and
EHTs are composed of a mix of spindle and epithelial psammoma bodies have been reported. There is no
cells, with islands of mature adipose tissue (Fig. 21.9). The cytologic atypia, mitotic activity is very low, and necrosis
spindle cells are an admixture of plump and delicate cells; is absent. Rare cases with malignant transformation are
the epithelial component may show squamous, glandular, documented.

FIGURE 21.9
Tumor is composed of spindle cells
entrapping epithelial and mature adipose
tissue components.

FIGURE 21.10
Spindle cell component with fascicular
arrangement; epithelial component with
glands and cystic structures.
CHAPTER 21  Benign Neoplasms of the Neck (Soft Tissue, Bone, and Lymph Node) 517

FIGURE 21.11
Epithelial component showing interanas-
tomotic strands of squamous cells.

tumor is negative for S100 protein and glial fibrillary

ECTOPIC HAMARTOMATOUS THYMOMA— acidic protein, while rarely showing focal reactivity
PATHOLOGIC FEATURES with CD34.
Gross Findings
■ Well-circumscribed mass, nonencapsulated

DIFFERENTIAL DIAGNOSIS
Microscopic Findings
■ Triphasic histology: spindle cells (predominant, bland, plump to

thin); epithelioid nests and cords haphazardously arranged The differential diagnosis includes mixed tumors of skin
(squamous, glandular, clear cells); mature adipocytes adnexal or salivary gland origin (EHT lacks chondroid/
■ No immature T cells
cartilaginous foci), spindle cell/pleomorphic lipoma
■ No evidence of thymic differentiation
(CD34-positive), sarcomatoid carcinoma (cytologically
Ancillary Studies malignant), synovial sarcoma, cystic teratoma (the origin
■ Smooth muscle actin-, keratin-, p63-positive is deep-seated), and glandular malignant peripheral nerve
■ Occasional CD34 positivity sheath tumor (patchy S100 protein and strong SOX10
positivity).
Pathologic Differential Diagnosis
■ Mixed tumors of skin adnexal or salivary gland origin, spindle

cell/pleomorphic lipoma, sarcomatoid carcinoma, synovial

sarcoma, cystic teratoma PROGNOSIS AND THERAPY

The tumor usually does not recur after local excision.

ANCILLARY STUDIES
■  SPINDLE CELL LIPOMA/
PLEOMORPHIC LIPOMA
IMMUNOHISTOCHEMICAL FINDINGS

The spindled areas display strong and diffuse positivity Spindle cell and pleomorphic lipomas are distinctive types
for cytokeratin and epithelial membrane antigen. Myo- of lipoma histologically on a continuum and characterized
epithelial phenotype with the coexpression of keratins by replacement of mature fat cells by bland spindle cells,
and smooth muscle actin has been also reported. The hyperchromatic round cells, and multinucleated giant
518 HEAD AND NECK PATHOLOGY

cells, including the characteristic “floret cell,” in associa- MICROSCOPIC FINDINGS

tion with ropy collagen. These tumors account for
approximately 1.5% of all adipose tissue neoplasms, with Microscopically, at one end of the histologic
a lipoma:spindle cell lipoma ratio of 60 : 1. spectrum, spindle cell lipoma is composed of varying
proportions of mature adipocytes and fibroblast-like

CLINICAL FEATURES
SPINDLE CELL LIPOMA/PLEOMORPHIC LIPOMA—DISEASE
FACT SHEET
More than 90% of spindle cell/pleomorphic lipomas occur
in men (men outnumbering women 10 : 1), with a peak Definition
■ A distinct group of lipomas composed of spindle cells,
incidence in the 6th decade. Almost all of the tumors
adipocytes, and multinucleated giant cells associated with ropy
are located in the subcutaneous tissue of the posterior
collagen
neck, upper back, and shoulder girdle. Rarely, the salivary
gland, lip, tongue, and maxillofacial region will be affected. Incidence and Location
Patients are usually asymptomatic but may present with ■ About 1.5% of all adipose tissue tumors

a painless, mobile, subcutaneous mass that has often ■ Subcutaneous tissues of posterior neck and upper back most

been present for many years. Characteristically, the tumors frequently

are solitary, although rarely they may be familial and
Sex and Age Distribution
multiple.
■ Males > > > females (10 : 1)
■ Mean age: 55 years

Clinical Features
PATHOLOGIC FEATURES ■ Painless, subcutaneous, mobile mass

■ Posterior neck, upper back, shoulders

■ Seldom multiple
GROSS FINDINGS
Prognosis and Treatment
Spindle cell/pleomorphic lipomas range in size from
■ Excellent, although there are isolated reports of recurrence
1 to 13 cm (mean, 5 cm). Grossly, they resemble an ■ Surgery
ordinary lipoma (Fig. 21.12), although some are gray-white
or pale-pink, and deeper tumors may be myxoid.

FIGURE 21.12
Well-circumscribed and encapsulated,
intramuscular spindle cell lipoma. Note
the myxoid appearance from low power
as well as areas of increased cellularity.
CHAPTER 21  Benign Neoplasms of the Neck (Soft Tissue, Bone, and Lymph Node) 519

FIGURE 21.13
Spindle cell lipoma with bland spindle
cells in a background of adipocytes. Note
the areas of thick, ropy collagen fibers.

A B

FIGURE 21.14
(A) Marked myxoid stroma with delicate collagen fibers and fibroblasts in a spindle cell lipoma. (B) Pleomorphic lipoma: Hyperchromatic nuclei are seen in
cells separated by dense collagen. There are a few floret-like (“petal”) multinucleated giant cells associated with mast cells and collagenized stroma.

spindle cells admixed with wire- or rope-like collagen At the opposite end of the spectrum lies pleomorphic
fibers (“ropy collagen”) and myxoid stroma (Figs. 21.13 lipoma, which is characterized by small, round hyper-
and 21.14). The fibroblast-like cells may be arranged chromatic cells and multinucleated giant cells with radially
in a parallel fashion. Mast cells are frequently numer- arranged “floret-like” nuclei—so named for their resem-
ous. It is important to note that fat may be sparse blance to the petals of a flower (Fig. 21.14). Cases with
and difficult to find in selected tumors. The myxoid mixed features of spindle cell and pleomorphic lipoma
stroma may be a dominant finding. Profound but focal occur quite often, making any distinction impossible and
nuclear pleomorphism can be seen and is considered arbitrary. Secondary changes of fat necrosis or hyaliniza-
“degenerative” or “ancient change.” Mitoses are usually tion can be seen and may also be associated with “aging”
absent. or “ancient” change. By definition, lipoblasts are absent.
520 HEAD AND NECK PATHOLOGY

lipomas (seen in about 70% of cases). These genetic

SPINDLE CELL LIPOMA/PLEOMORPHIC LIPOMA— findings support distinction from both conventional
PATHOLOGIC FEATURES lipoma and atypical lipomatous tumor/well-differentiated
liposarcoma (ALT/WDLPS). The same alteration is seen
Gross Findings
■ Yellow to gray-white to pale-pink circumscribed mass
in mammary-type myofibroblastoma, as well as in cellular
■ Mean, 5 cm (range, 1-13 cm) angiofibroma.

Microscopic Findings
■ Mixture of bland spindle cells arranged in parallel, adipocytes,

and multinucleated giant cells (“floret-like”)

DIFFERENTIAL DIAGNOSIS
■ Bands of mature rope-like collagen fibers

■ Mast cells may be numerous

The differential diagnosis includes ALT/WDLPS (owing
Ancillary Studies to the adipocytic component) and the common neural
■ Spindle cells of both types of lipoma express CD34 neoplasms, neurofibroma and schwannoma (owing to
■ Negative for S100 protein the spindle cell component); myxoma, nuchal fibroma,
■ Loss of 13q and/or 16q and fibrous hamartoma of infancy are occasionally
considerations. The uniformity of the spindle cells,
Pathologic Differential Diagnosis association with mature collagen fibers, and absence of
■ Atypical lipomatous tumor/well-differentiated liposarcoma,
lipoblasts—combined with the characteristic location,
neurofibroma, schwannoma, myxoma, nuchal fibroma
patient age, and overall circumscription of the lesion—
support the diagnosis of spindle cell lipoma over ALT/
WDLPS. Spindle cell/pleomorphic lipoma lacks the MDM2
amplification characteristic of ALT/WDLPS. Neurofibroma,
which tends to be infiltrative, contains spindle cells that
ANCILLARY STUDIES are more randomly arranged and may contain charac-
teristic Wagner-Meissner bodies (eosinophilic-appearing
ULTRASTRUCTURAL FINDINGS touch corpuscles). Schwannoma has buckled-wavy nuclei,
cellular Antoni A areas, and perivascular hyalinization.
Electron microscopic studies have revealed spindle S100 protein and SOX10 are usually strongly and diffusely
cells thought to represent fibroblasts or fibroblast-like immunoreactive. Myxoma is very hypocellular, lacks fat,
cells analogous to the stellate mesenchymal cells seen in and does not have thick bundles of collagen. A nuchal-type
primitive fat lobules. fibroma has fat but has a much heavier collagen deposition
and entrapped nerves. Fibrous hamartoma of infancy most
IMMUNOHISTOCHEMICAL FINDINGS commonly involves soft tissue of shoulder, axilla, and
upper arm in infants (within the first 2 years of life). It
Immunohistochemically, the spindle cells in spindle/ is composed of three distinctive tissue types: (1) well-
pleomorphic lipomas express CD34 and vimentin. Rare differentiated fibroblastic/myofibroblastic cells, (2) mature
isolated cells may be positive for S100 protein, but this adipose tissue, and (3) whorls of primitive mesenchymal
is quite different from the strong reaction usually seen areas.
in ordinary lipocytes. MDM2 immunostaining is
negative.
PROGNOSIS AND THERAPY
FINE NEEDLE ASPIRATION

Smears will contain large, atypical, floret-type cells Complete local excision is curative for both types of
within a background of mature adipocytes. Needless to lipomas.
say the cells are frequently interpreted to be malignant.

MOLECULAR STUDIES SUGGESTED READINGS

The complete Suggested Readings list is available online at
Loss of chromosomes 13q (13q12 and 13q14-q22) and/ ExpertConsult.com.
or 16q (16q13-qter) is characteristic of this family of
CHAPTER 21  Benign Neoplasms of the Neck (Soft Tissue, Bone, and Lymph Node) 520.e1

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