Benign
tumours
Adenoma
Adenomas arise in secretory glands, and resemble the structure from
which they arise. They are encapsulated, and sometimes they secrete hormones
which profoundly influence metabolism, as in the case of the thyroid,
parathyroid and pancreas. Occasionaliy an adenoma contains a large proportion of
fibrous tissue, e.g. the hard fibroadenoma in the breast, while in other
situations, notably the pancreas and thyroid gland, cystic degeneration is
common. Those arising from superficial glands of mucous membrane are liable to
pedunculation, as in the case of a rectal ‘polyp,.
Papilloma
A papilloma consists of a central axis of connective tissue, blood
vessels and lymphatics; the surface is covered by epithelium, either squamous,
transitional, cuboidal or columnar, according to the site of the tumour. The
surface may be merely roughened, or composed of innumerable delicate villous
processes, as in the case of those occurring in the kidney, bladder and rectum.
In these situations, papillomas resemble malignant rumours, as secondary growths
arise by implantation and, sooner or later, the tumour becomes frankly malignant
(Chapter 65). Other common sites for papillomas are the skin, the colon,
the tongue and lip, t] vocal cords and the walls of cysts (particularly those
the breast and ovary).
Fibroma
A true fibroma (containing only fibrous connective tissue) rare. Most
fibromas are combined with other mesoderm tissues such as muscle (fibromyoma),
fat (fibrolipoma) ai nerve sheaths (neurofibroma). Multiple rumours are n
uncommon as, for example, in neurofibrornatosis (v Recklinghausen’s disease,
Fig. 12.7).
Fibromas
are either hard or soft, depending on the propc non of fibrous to the
other cellular tissue. Soft fibromas a common in the subcutaneous tissue of the
face, and appear soft, brown swellings.
[This unusual type of flbroma occurs in the abdominal wall (see Chapt
62). An intraperitoneal form is associated with familial adenomato polyposis
(see Chapter 57).
A lipoma is a slowly growing tumour composed of fat cells adult type.
Lipomas may be encapsulated or diffuse. Tb occur anywhere in the body where fat
is found and earn tl titles of the ‘universal tumour’ or the ‘ubiquitous
tumour The head and neck area, abdominal wall and thighs are particularly
favoured sites.
Encapsulated
lipomas are among the commonest of
rumours. The characteristic features are the presence of a definite edge and
lobulation. A sense of fluctuation may be obtained. As would be expected, a
lipoma deeply situated is liable to be mistaken for other swellings. Most
lipomas are painless, but some give rise to an aching sensation which may
radiate.
Multiple
lipomas are not uncommon. The rumours
remain small or moderate in size, and are sometimes painful, in which case the
condition is probably one of neurolipomatosis. Dercum ‘s disease (adiposis
dolorosa), characterised
by tender deposits of fat, especially on the trunk, is an associated
condition.
Should
the lipoma contain an excessive amount of fibrous tissue, it is termed a fibrolipoma.
In other cases, considerable vascularity is present, often with
telangiectasis of the overlying skin, in which case the tumour is a naevolipoma.
Large lipomas of the thigh (Fig. 12.8), the shoulder
(Fig. 12.9) and the
retroperitoneum occasionally undergo sarcomatous changes. Myxomatous
degeneration, saponification and calcification sometimes occur in
lipomas of long duration.
Clinically, circumscribed lipomas are classified according to their
Situation.
• Subcutaneous. Commonly
found on the shoulders or the back, although no part of the body is immune. A
lipoma may be present over the site of a spina bifida. Subcutaneous lipomas
occasionally become pedunculated (lipoma arborescens).
• Sub fascial. Occurring
under the palmar or plantar fascia, they are liable to be mistaken for
tuberculous tenosynovitis, as the tough, overlying fascia masks the definite
edge and lobulation of the tumour. Difficulty is encountered in complete removal
as pressure encourages the tumour to ramify. Subfascial lipomas also occur in
the areolar layer under the epicranial aponeurosis and, if of long duration,
they erode the underlying bone, so that a depression is palpable on pushing the
tumour to one side.
• Subs ynovial. From
the fatty padding around joints, especially the knee. In the knee, they are apt
to be mistaken for Baker’s cysts but are easily distinguished as, in
distinction to a cyst or bursa, their consistency is constant whether the joint
is in extension or flexion.
• Intra-articular.
• Intenmuscular. Mainly
in the thigh or around the shoulder. Owing to transmitted pressure, the tumour
becomes firmer when the adjacent muscles are contracted. Weakness or aching
results, owing to mechanical interference with muscular action. The condition
is often difficult to distinguish from a fibrosarcoma.
• Panosteal occasionally
occur under the periosteum of a bone.
• Subserous are
sometimes found beneath the pleura, where they constitute one variety of
innocent thoracic tumour. A retroperitoneal lipoma may grow to enormous
dimensions, and simulate a hydronephrosis or pancreatic cyst.
• Submucous occur under
the mucous membrane of the respiratory or alimentary tracts. Rarely a submucous
Iipoma in the larynx causes respiratory obstruction. A submucous lipoma can
occur in the tongue. One situated in the intestine is likely to cause an
intussusception, which may be the first indication of its presence.
• Central nervous system. Lipomas
may occur anywhere within the extradural spaces, the spinal cord and brain; they
usually arise from the pia mater, within the central subarachnoid spaces
(especially the quadrigeminal cisterns); a lipoma of the corpus callosum may be
accompanied by calcification on the convex margins.
• Intraglandular. Lipomas
have been found occasionally in the pancreas, under the renal capsule and in the
breast (Chapter 46).
• Retropenitoneal. Large
lipomas are seen not infrequently in the retroperitoneal tissues. Some of them
turn Out to be liposarcomas.
Treatment
During
operation, any finger-like projections of the tumour into the surrounding tissue
should also be removed. Although the tumour is relatively avascular, care is
needed to obtain complete haemostasis in the resulting cavity otherwise a
haematoma is common, which may be followed by infection and delay in wound
healing; drainage is often necessary.
Diffuse
lipoma occasionally occurs in the
subcutaneous tissue of the neck, from which it spreads on to the preauricular
region of the face. The tumour is not obviously encapsulated, and gives rise to
no trouble, beyond being unsightly.
Neuroma
True neuromas are rare rumours, and occur in connection with the
sympathetic system. They comprise the following types:
• Ganglioneuroma, which
consist of ganglion cells and nerve fibres. It arises in connection with the
sympathetic ganglia, and therefore is found in the retroperitoneal tissue, or in
the neck or thorax.
• Neuroblastoina, which
is less differentiated than the ganglioneuroma, the cells being of an embryonic
type. The tumour somewhat resembles a round-celled sarcoma, and disseminates by
the bloodstream. It occurs in infants and young children. It may occasionally
undergo spontaneous remission.
• Myelinic neuroma is
very rare, being composed only of nerve fibres, as the ganglion cells are
absent. They arise in connection with the spinal cord or pia mater.
Neurofibroma arise from the connective tissue of the nerve sheath. The
following varieties are described.
A single neurofibroma is usually found in the subcutaneous tissue. The
‘painful subcutaneous nodule’ forms a smooth firm swelling which may be
moved in a lateral direction, but is otherwise fixed by the nerve from which it
arises. Paraesthesia or pain is likely to occur from the pressure of the tumour
on the nerve fibres which are spread over its surface. Cystic degeneration or
sarcomatous changes occur occasionally.
Neurofibromas
may also grow from the sheath of a peripheral nerve or a cranial nerve, e.g. the
acoustic tumour (Chapter 35). As the nerve fibres are ‘part and
parcel’ of the tumour they are difficult to remove without removal of the
nerve itself. In major nerves recurrence is a problem, as is malignant (sarcomatous)
change.
(syn.
von Rechlinghausen’s disease of nerves)
In this inherited (autosomal-dominant) disease, any cranial, spinal or
peripheral nerve may be diffusely or modularly thickened (Fig.
12.7). The
overgrowth occurs in connection with the endoneurium. Associated pigmentation (cafe
au lait) of the skin is common, and sarcomatous changes may occur.
Plexiform
neurofibromatosis
This rare condition usually occurs in connection with branches of the
fifth cranial nerve (Fig. 12.11), although it may occur in the extremities
(Fig. 12.12). The affected nerves become enormously thickened as a result of
myxofibromatous degeneration of the endoneuriurn.
Elephantiasis
neuromatosa
Elephantiasis neuromatosa is a rare variant congenital condition. The
skin is coarse, dry and thickened, resembling an elephant’s hide, and the
subcutaneous tissues become greatly thickened. If a leg is affected, the patient
finds walking increasingly difficult. A famous patient of the London Hospital
with this condition (the ‘Elephant Man’) was befriended by his surgeon, Sir
Frederick Treves (see also Fig 12.11 and
Fig 12.12).
Arises from the connective tissue of the nerve sheath after injury to a
nerve (lacerations or amputation). These swellings consist of fibrous tissue and
coiled nerve fibres.
Haemangiomas are described in Chapter 13. They are represented in
various forms, capillary, cavernous and plexiform being common.
Glomangioma
(syn. glomus tumour)
These rumours arise from a cutaneous glomus composed of a tortuous
arteriole which communicates directly with a venule, the vessels being
surrounded with a network of small nerves. These specialised organs regulate the
temperature of the skin, and are found in the limbs, especially the nail beds.
The tumour is compressible. The associated pain is out of all proportion to the
size of the tumour, which may be only a few millimetres in diameter. The pain is
burning in nature and radiates peripherally, and is more often noticeable when
the limb is exposed to sudden changes in temperature.
On
section the tumour consists of a mixture of blood spaces, nerve tissue and
muscle fibres derived from the wall of the arteriole (angiomyoneuroma). Large
cuboidal cells are frequently seen (glomal cells). Cutaneous glomus rumours grow
very slowly, and do not become malignant. They should be excised.
The term hamartoma is roughly translated from the Greek as a
‘fault’, and its original meaning was ‘missing the mark in spear
throwing’. It is a developmental malformation consisting of overgrowth of
tissue or tissues proper to the part. The possible range therefore is very wide
and the lesions are often multiple. Common lesions that are hamartomas are
benign pigmented moles, and the majority of angiomas and neurofibromas. On
rare occasions a malignant change occurs in a hamartoma, but for practical
purposes the lesion is benign (Peters).