Section 8: Cutaneous neoplasia
Chapter 39: Soft Tissue Tumours
Introduction
Soft-tissue tumours arise in the dermis,
subcutis or deeper soft tissues. Most of these
tumours have no characteristic clinical
appearance, and present as non-specific,
dermal, or deep-seated nodules. Smaller
lesions carry a better prognosis. More
superficially situated lesions tend to carry a
better prognosis than those deeply situated.
Malignant soft-tissue tumours are rare. Some
tumours have low-grade malignant potential
e.g.
dermatofibrosarcoma
protuberans.
Treatment of soft-tissue tumours is usually by
surgical excision. Once the pathologist has
established the nature of the tumour,
appropriate definitive surgery can be
determined.
Fibrous tumours
Fibrous papule of the face
This common lesion is usually a single
papule on the nose, occasionally multiple or
occurring on other parts of the face, and is
dome-shaped, small, skin-coloured, sessile,
asymptomatic and can be excised for cosmetic
reasons.
Acquired digital fibrokeratoma
A solitary dome-shaped lesion, with a
collarette of slightly raised skin at its base,
occurs on the fingers and toes, resembles
dermatofibroma or viral wart, and is treated by
excision.
Nodular fasciitis
A rapidly enlarging, tender subcutaneous
nodule, 1-3 cm in diameter, occurring
anywhere but most commonly the upper
extremities, which is due to benign
proliferation of myofibroblasts and fibroblasts
and histologically has a superficial
resemblance to a sarcoma due to numerous
mitoses but there are no abnormal cells.
Treatment is excision.
Fibrous hamartoma of infancy
A rapidly growing, solitary, deep dermal
and subcutaneous benign tumour, a few
centimeters in diameter, occurring in children
below age of 2 years, with a predilection for
the axillae, arm and shoulder girdle, and is
treated by excision.
Dermatomyofibroma
A benign, solitary, asymptomatic, skincoloured
dermal
and
superficially
subcutaneous plaque, that measures less than 4
cm in diameter, occurring on the trunk in
young adults, and is treated by excision.
Elastofibroma
An asymptomatic benign mass around
the shoulder of middle-aged individuals due to
degeneration of elastic fibres and is treated by
excision.
Palmar and planter fibromatosis
This disorder (Dupuytren's contracture) is
a superficial neoplastic proliferation of
fibroblasts and myofibroblasts that have a
tendency for local recurrence, but do not
metastasize. Genetic predisposition and
trauma may play an important part in the
pathogenesis. The tumour occurs in middleaged or elderly patients and may be associated
with Peyronie’s disease or Knuckle pads.
Palmar fibromatosis presents as indurated
nodules or as an ill-defined area of thickening,
bilateral in 50% of cases, that may result in
contractures. Planter fibromatosis usually
consists of a single nodule. Functional
limitation is common. Treatment is complete
excision.
Dermatofibrosarcoma protuberans
Aetiology: A locally invasive tumour arising
in the dermis, showing fibroblastic
differentiation, and occurs in middle age.
Clinical features: The progression of the
tumour is slow, over many years. It is more
often situated on the trunk than on the
extremities or head. Presentation is with small,
firm, painless, flesh-coloured or red dermal
nodules, which increase in size, coalesce and
extend, becoming redder or bluish as they
enlarge to form irregular, protuberant
swellings, having a hard, indurated, irregular
base. The lesions may become painful or
ulcerate. Local recurrence occurs in 15% of
cases. However, in the sarcomatous variant
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recurrence is 75% and metastases occur in
20%.
Pathology: The dermis and subcutaneous
tissue are replaced by bundles of uniform
spindle-shaped cells with little cytoplasm and
elongated
hyperchromatic,
but
not
pleomorphic, nuclei. Usually there is little
mitotic activity. Laterally, the tumour cells
infiltrate widely between collagen bundles of
the deeper dermis and blend into the normal
dermis, forming quite definite bands, which
interweave or radiate like spokes of a wheel;
this is described as a ‘storiform’ pattern. The
subcutaneous tissue is extensively infiltrated.
In the fibrosarcomatous variant, mitoses are
increased and there is more nuclear
hyperchromatism.
Treatment: The tumour should be excised
completely, with a generous margin of healthy
tissue as local recurrence invariably follows
inadequate removal.
Fibrohistiocytic tumours
Fibrous histiocytoma
This disorder (dermatofibroma, FH) is a
benign dermal and often superficial
subcutaneous proliferation of oval cells
resembling histiocytes, and spindle-shaped
cells
resembling
fibroblasts
and
myofibroblasts. It is most common on the
limbs and presents as a firm, yellow brown,
slightly scaly papule. If the overlying
epidermis is squeezed the ‘dimple sign’ will
be seen, indicating tethering of the overlying
epidermis to the underlying lesion. Giant
lesions (more than 5 cm in diameter) are
occasionally seen. Clinical variants include
cellular FH, aneurysmal FH, atypical FH and
epithelioid FH.
The
pathology
shows
epidermal
hyperplasia. In the dermis, there is a localized
proliferation of histiocyte-like and fibroblastlike cells, associated with a variable number of
mononuclear inflammatory cells. Foamy
macrophages, siderophages and multinucleated giant cells are also variably present.
A focal storiform pattern is often seen.
Collagen bundles at the periphery of the lesion
are surrounded by scattered tumour cells and
appear
somewhat
hyalinized.
Histopathological variants exist including cellular
FH, aneurysmal FH, atypical FH and
epithelioid FH.
Most FHs are of cosmetic importance
only and no treatment is necessary. However,
cellular, aneurysmal and atypical variants
should be completely removed, because of the
risk of local recurrence.
Vascular tumours
Reactive angioendotheliomatosis
A reactive vascular proliferation, which
is usually multifocal and which is associated
with a number of systemic diseases including
bacterial endocarditis, peripheral vascular
atherosclerotic disease, cryoglobulinaemia,
antiphospholipid syndrome, amyloidosis and
liver and renal disease. Most patients present
with
multiple
erythematous
and/or
haemorrhagic macules, papules and plaques
on the trunk and limbs. The dermis shows a
multifocal proliferation of clusters of
capillaries lined by plump endothelial cells.
The condition usually resolves spontaneously
within a few weeks.
Pyogenic granuloma
Aetiology:
This
disorder
(granuloma
telangiectaticum) is common, occurs at any
age and is probably a reactive lesion. A
vascular nodule develops rapidly, often at the
site of a recent injury, and is composed of a
lobular proliferation of capillaries in a loose
stroma.
Pathology: The endothelial cells are plump, as
in new granulation tissue, lining the vessels in
a single layer. The proliferating vessels are set
in a myxoid stroma rich in mucin. There is a
mixed cell population of fibroblasts, mast
cells, lymphocytes and plasma cells. Mitotic
figures may be prominent. Older lesions tend
to organize and partly fibrose.
Clinical features: The tumour is vascular,
bright red or blue-black, rounded, 5-10 mm up
to 50 mm in diameter, compressible, the base
is often pedunculated and surrounded by a
collar of epidermis, and the surface may b
eroded and it bleeds easily.
Treatment: By curettage with cauterization or
diathermy coagulation of the base. Other
treatment modalities that have been used
include topical imiquimod 5% cream,
cryosurgery, Nd: YAG laser, flash lamp
pulsed dye laser, intralesional steroids and
even injection of absolute ethanol.
Epithelioid haemangioma
This
disorder
(angiolymphoid
hyperplasia
with
eosinophilia,
pseudopyogenic granuloma) is a benign
locally proliferative lesion composed of
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vascular channels lined by endothelial cells
having abundant pink cytoplasm and vesicular
nuclei, associated with an inflammatory
infiltrate composed mainly of lymphocytes
and large numbers of eosinophils. Affected
individuals are commonly young adults, who
present with a cluster of small, translucent
nodules on the head and neck, particularly
around the ear or the hairline. Spontaneous
remission occurs in the majority of cases.
Peripheral blood eosinophilia occurs in 10%
of cases. It is reasonable to observe the lesion
for 3-6 months and await spontaneous
regression. Both surgery and radiotherapy are
effective, but local recurrences are common.
Kaposi’s sarcoma (KS)
Definition: KS is a multifocal endothelial
proliferation predominantly involving the skin
and other organs and associated with
formation of vascular channels and
proliferation of spindle-shaped cells. It is
induced by herpesvirus HHV8 which is
present in all KS patients. This virus, along
with
genetic,
environmental
and
immunological factors is closely involved in
the pathogenesis of KS. The disease starts as a
reactive angioproliferative and inflammatory
process but progresses to become a neoplastic
process. The proliferating cells are endothelial
cells with lymphatic differentiation. There are
4 clinical types of KS: classic, endemic,
iatrogenic and HIV-related.
 Classic KS: Occurs in elderly males and
the lesions begin slowly and insidiously
around the ankle and slowly spread up the leg.
Lymphoedema can occur as a complication.
Involvement of internal organs and death from
the disease is not usually seen.
 Endemic KS: Occurs in equatorial Africa,
predominantly in adult males, but children can
be affected. Crops of cutaneous vascular
lesions develop and may be associated with
gross oedema. Visceral lesions may occur
leading to a poor prognosis. The condition
responds to chemotherapy.
 Iatrogenic KS: Occurs in transplant
patients and after cytotoxic chemotherapy for
lymphomas. Both systemic and cutaneous
lesions may occur and the progress may be
aggressive leading to death. If it is possible to
remove the immunosuppression, the lesions
will regress.
 KS associated with HIV infection: This is
much commoner in homosexuals than in drug
abusers. It usually develops in the later stages
of the disease. The lesions may occur
anywhere on the body with explosive rapidity
and become large nodules. Involvement of
lymph nodes, lungs and GIT is common. Both
radiotherapy
and
chemotherapy
give
temporary benefit and the prognosis is poor.
Pathology: The skin lesions can be divided
into patch, plaque and nodular stages. In the
patch stage there is proliferation of irregular,
lymphatic-like vascular channels lined by a
single layer of endothelial cells, surrounding
normal pre-existing capillaries and adnexal
structures, which seem to be floating within
the newly formed channels, the so-called
‘promontory sign’. A patchy inflammatory
mononuclear cell infiltrate containing plasma
cells is seen. This is associated with
extravasation of red blood cells and
haemosiderin deposition.
The plaque stage is an exaggeration of
the patch stage. The vascular channels
increase in number and a network of spindleshaped cells with pink cytoplasm develops.
Eosinophilic globules are common, and
probably represent degenerate red blood cells.
Involvement of the whole dermis and
superficial subcutis is frequent.
In the nodular stage, there are fairly wellcircumscribed nodules of spindle-shaped cells
forming frequent cleft-like spaces that impart
a typical sieve-like appearance. Extravasated
RBCs are plentiful, as are hyaline globules.
Mitotic figures are common. A useful aid in
the histological diagnosis of KS is monoclonal
antibody against HHV8, which stains tumour
cells in all cases of the disease.
Clinical features: KS tends to occur in males.
The lesions have a dark-blue or purplish
colour. Initially they may be macular and
when they become tumid, pressure may
produce partial blanching to reveal a brown
tinge. The process usually bengins on the
extremities, most commonly on the feet, and
occasionally on the hands, ears or nose.
Individual tumors enlarge to a diameter of 1-3
cm and stop growing. The process is
multifocal, and adjacent areas may fuse to
form a plaque or tumour. Oedema of the limb
may occur and nodules on pressure areas may
be painful. The rate of spread is remarkably
variable. The lesions may involute to leave
pigmented scars, or may become eroded,
ulcerated or fungating. Lymph nodes, mucosal
surfaces and internal organs, may be involved
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as the disease progresses. KS may occur in
internal organs without skin manifestations. In
KS due to immunosuppression, there may be
only one or 2 lesions scattered over the body.
Differential diagnosis: The evolution of KS
from a macular lesion and its characteristic
colour, slow development and multifocal
distribution makes the diagnosis likely in most
cases.
Pseudo-Kaposi’s
sarcoma
(acroangiodermatitis) occurs in prolonged
venous stasis of the lower legs, lack
progression and spindle-cell proliferation.
Treatment: Where a small area is involved,
excision or radiotherapy can be used.
Superficial radiotherapy is rapid and effective,
and is the treatment of choice for the majority
of patients with nodular disease of the
extremities. Extensive disease can be treated
by cytotoxic drugs such as chlorambucil,
cyclophosphamide,
vinblastine
or
actinomycin. Cases related to AIDS may
respond to intralesional vinblastine or
vincristine, IL-2 or interferon. Pegylated
liposomal doxorubicin is a successful
treatment of advanced classic KS and cases
associated with AIDS.
Angiosarcoma
Definition: A malignant vascular tumour,
arising from both vascular and lymphatic
endothelium. It occurs in 3 settings:
idiopathic angiosarcoma of the face, scalp
and neck, angiosarcoma associated with
chronic
lymphoedema
(Stewart-Treves
syndrome) and post-irradiation angiosarcoma.
Stewart-Treves syndrome occurs in 5% of
patients who survive mastectomy for more
than 5 years.
Pathology: Vascular channels infiltrate the
normal structures in a disorganized fashion.
They are thin-walled, irregular and are lined
by atypical endothelial cells which form solid
intravascular buds. Haemorrhage is often
prominent. Immunohistochemical studies
have indicated that the antibodies to CD31
are the most reliable markers.
Clinical features: In all types of angiosarcoma
the first sign may be an area of bruising.
Dusky blue or red nodules develop and grow
rapidly, and fresh discrete nodules appear
nearby. In some cases, haemorrhagic blisters
are a prominent feature. As the tumours grow,
the oedema may increase and older lesions
may ulcerate. Multifocality is very frequent.
Dissemination occurs early, with the first
visceral deposits usually being in the lung and
pleural cavity. The 5-year survival is about
12%.
Treatment: All angiosarcomas have a bad
prognosis. Wide excision and grafting has
controlled some cases. The response to
radiotherapy is disappointing and is usually
only palliative.
Tumours of perivascular cells
Glomus tumour
Definition: A tumour of the myoarterial
glomus composed of vascular channels
surrounded by proliferating glomus cells. The
tumour has variable quantities of glomus cells,
blood vessels and smooth muscle. According
to this finding, they are classified as solid
glomus
tumour,
glomangioma
and
glomangiomyoma.
Pathology: The tumour is round wellcircumscribed and situated in the dermis. The
proportion of glomus cells to vascular spaces
varies. The smaller, painful lesions tend to be
mainly cellular (solid glomus tumour, in 35%
of cases). The larger, multiple and often
painless
lesions
are
angiomatous
(glomangiomas, in 50% of cases), with only a
band of cells around the dilated vascular
channels. Glomangiomyomas are a minority
(15%). The glomus cells are cuboidal, with a
well-marked cell membrane and a round
central nucleus. The cells align themselves in
rows around the single layer of endothelial
cells of the vascular spaces. Numerous nonmyelinated nerve fibres course through the
cellular masses.
Clinical features: A solitary glomus tumour
is a pink or purple nodule varying in size
from 1 to 20 mm and is conspicuously
painful. Pain may be provoked by direct
pressure or a change in skin temperature, or
may be spontaneous. The commonest site is
the hands, particularly the fingers, followed
by the extremities, head, neck and penis.
Tumours beneath the nail are particularly
painful and the nail has a bluish-red flush.
Multiple glomus tumours are larger and
usually dark blue in colour, and are situated
deep in the dermis. They may be widely
scattered and are not usually painful.
Treatment: Surgical excision is usually
curative.
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Neural tumours
Tumours of smooth muscle
Schwannoma
Definition: A tumour of nerve sheaths
composed of Schwann cells. It arises most
frequently from the acoustic nerve. Bilateral
acoustic Schwannomas are characteristic of
neurofibromatosis type 2. In the peripheral
nervous system, it is usually found in
association with one of the main nerves of the
limbs.
Pathology: The tumour is rounded,
circumscribed and encapsulated. It is situated
in the course of a nerve, usually in the
subcutaneous fat. The cells are spindle
shaped with a poorly defined cytoplasm and
elongated wavy basophilic nuclei. Variable
amounts of collagen are seen in the
background. Cells are arranged in bands, and
their nuclei are arranged in rows with
intervening eosinophilic cytoplasm in a
typical appearance known as verocay bodies.
There are several histopathological types
which include ancient, cellular, plexiform,
melanotic,
pacinian
and
glandular
Schwannomas.
Clinical features: Lesions are nodules:
rounded or oval, firm, grow slowly,
circumscribed, up to 5 cm size, pink-grey or
yellowish, small lesions may be intradermal
but larger ones are subcutaneous.
Deferential diagnosis: Of the various nodular
dermal
and
hypodermal
tumours,
Schwannoma is most likely to be mistaken for
a glomus tumor when painful, and for lipoma,
epidermoid cyst, juxta-articular node or
neurofibroma when asymptomatic. The
diagnosis is suspected when it is in the course
of a nerve.
Treatment: Surgical excision.
Leiomyoma
There are 3 clinical types of leiomyoma:
Pilar, genital and angioleiomyoma. Pilar
leiomyoma (leiomyoma cutis) originates in the
pilomotor muscle, is the most frequent type
and occurs at any age. It presents as a
collection of multiple, pink, red or dusky
brown, firm dermal nodules of varying size
but usually less than 15 mm diameter. The
nodules most commonly occur on the
extremities and may evolve to form a plaque.
The nodules are often subject to episodes of
pain provoked by touch or cold, and may be
tender. The lesions may contract and become
paler when painful.
Genital leiomyoma is a solitary dermal
nodule arising in the smooth muscle of the
genitalia (scrotum, penis, labia majora) and
areola of the nipple and occurs at any age.
Scrotal tumours are often large. Pain is less
frequent than with leiomyoma cutis and
contraction in response to stimulation by touch
or cold can occur.
Angioleiomyoma is a solitary, fleshcoloured, rounded, subcutaneous or deep
dermal tumour, arising from the muscular coat
of veins, occurring in middle age, usually on a
limb. Diameter is up to 40 mm and it is painful
in 50% of cases, pain being triggered by cold,
pregnancy or menses.
Leiomyoma is a benign tumour of smooth
muscle and the pathology shows smooth muscle
cells proliferating to produce interweaving
bundles of spindle-shaped cells, which are
strongly eosinophilic, having long and thin
nuclei. Multiple cutaneous leiomyomas is
composed of numerous dermal nodules which
show
epidermal
hyperplasia.
Genital
leiomyomas are nodular tumours with a similar
appearance. The angiomyomas are related to
veins in the subcutaneous tissue, showing
vessels of variable thickness intermixed with
bundles of mature smooth cells.
The solitary painful lesion may be mistaken
for a glomus tumour or an eccrine spiradenoma,
and the history of contraction on cold exposure is
helpful in diagnosis. Surgical excision cures the
solitary tumour, but extensive lesions require
plastic surgery. Medical treatment that may
relieve pain include calcium-channel blockers
and gabapentin.
Plexiform neurofibroma
This tumour is pathognomonic for
neurofibromatosis type 1. It presents in
children and young adults with predilection
for the lower limbs and the head and neck.
Tumours are large and located in the dermis,
subcutis and deeper soft tissues. The overlying
skin is folded and hyperpigmented and the
lesion is described as having the appearance of
a ‘bag of worms’. Surgical removal is usually
very difficult due to tendency for
haemorrhage.
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