Malignant
lesions
Basal
cell carcinoma
Basal cell carcinoma (BCC, rodent ulcer) is the commonest form of skin
cancer and typically affects individuals between the ages of 40 and 79 years;
more than 50 per cent are male and more than 85 pet cent of these lesions occur
in the head and neck region. These tumours are thought to originate
• nodular: 50—54 per cent;
• superficial: 9—11 per cent;
• cystic: 4—8 per cent;
• pigmented: 6 per cent;
• morpheic: 2 per cent.
• Electrodessication and curettage
commonly used for small superficial lesions (2—5 mm in diameter) gives cure
rates between 85 and 100 per cent.
• Radiotherapy. BCC is very
radiosensitive and has an overall response of 92 per cent in selected patients.
This is reserved for elderly patients who are not suitable for surgery or for
specialised anatomical sites.
• Mob’s micrographic surgery (chemosurgery) involving serial
horizontal excision and mapping of the tumour. Usually reserved for recurrent
lesions, tumours in difficult areas or those with indistinct borders (morpeaform).
• Radiotherapy should be used for massive unresectable tumours
in critical anatomical sites. Postoperatively it may be used for
persisting tumour or where clearance is doubtful.
Verrucous carcinoma are well-differentiated SCC which invade locally but
rarely metastasise. These commonly occur on the palm and soles; here they are
known as carcinoma ciniculatum
Keratoacanthoma
Keratoacanthoma (molluscum sebaceum) (Fig. 13.38) arises as a rapid
proliferation of squamous epidermal cells. The nodule grows rapidly for 6—8
weeks at which time it usually begins to resolve spontaneously. Keratoacanthoma
must be distinguished from 8CC. Usually rapid evolution to relatively large
size, irregular crater shape and keratotic plug, and the undamaged surrounding
skin make a distinction possible. Spontaneous healing further confirms
the diagnosis.
Melanoma
Cutaneous melanoma is a malignant neoplasm arising from epidermal
melanocytes. The earliest description is in the writings of Hippocrates in the
fifth century BC. John Hunter described a ‘cancerous fungous excrescence’ in
1787, which has subsequently been diagnosed as a melanoma. It has been
considered a rare tumour with unpredictable behaviour. It varies from
spontaneous regression to rapid progression and death. However, the disease is
no longer rare. The rate of increase in the incidence of melanoma is greater
than for any other cancer in Caucasians with the exception of bronchogenic
carcinoma. Its incidence has doubled every 10 years in countries close to the
equator and every 10—15 years in more temperate zones. Incidence has
quadrupled in Australasia and doubled in Norway, Britain, America and Canada in
the last 30 years. This increase in incidence is not observed in other skin
cancers. The incidence is 40 per 100 000 in Queens land, Australia, but only 4
per 100 000 in Scotland. It accounts for almost all the deaths from skin cancer.
It
is likely that between a third and a half of all melanomas develop in a benign
naevus of many years’ standing. Melanoma does not exhibit any overall sex
predilection. The commonest site for females is the lower leg and in males the
front or back of the trunk. In the Bantu, the sole of the foot is the most
frequent site; they can also occur on the palms and other depigmented areas, but
do not arise in the black skin of the remainder of the body for a reason that is
not understood. Rarely, melanoma arises in the eye, in the meninges or at the
mucocutaneous junction zones, e.g. anus and mouth. There is now strong evidence
that the increase in exposure to sunlight is mainly responsible for the rapid
increase in this skin cancer. It is well known that solar irradiation, which is
now much more dangerous as a result of the decreasing ozone layer, is associated
with all skin cancers. Ethnic origin, climate, socioeconomic status and
lifestyle are all risk factors interacting with sun exposure. The other evidence
with reference to sun exposure is that patients with pathological conditions,
such as albinism and xeroderma pigmentosa, are susceptible to forming melanomas.
A proportion will arise in a Hutchinson’s freckle (see below). Clark et al.
in 1975 produced a concept of a ‘radial growth phase’ to describe the
atypical proliferation of intraepidermal melanocytes which precedes the
development of dermal invasion (vertical growth phase) in all except nodular
melanoma.
Four
parameters of histological grading are used, as follows.
2. Ulceration, and
3. a high mitotic rate carry a poor prognosis.
4.Regression, if present,
for some thin melanomas may have an appreciable risk of metastases, presumably
because the lesion at some point in the past had been of a sufficient thickness
to have metastasised.
Clinical
features
Clinically, five types are recognised:
• lentigo maligna;
• superficial spreading;
• nodular;
• acral-lentiginous;
• amelanotic.
Superficial
spreading melanomas are the most common (64 per cent). They occur on any part of
the body and are usually greater than 0.5 mm in diameter. A variegated coloured
pattern and an irregular edge are characteristic. The lesion is usually
palpable.
Nodular
melanoma. This is the most malignant, occurring in about 12—25 per cent of
cases and found in the younger age groups. It may occur on any part of the body,
and is
Lentigo
maligna melanoma (Hutchinson’s melanotic freckle) is the least common (7—15
per cent) and least malignant. It occurs most frequently on the face in people
aged over 60 years. It may occur on any part of the body habitually exposed to
the sun. It begins as an irregularly pigmented, flat, brown macule which grows
very slowly over a period of 1—15 years, advancing and regressing in various
areas. There is a great variation in colour from brown to tanned black within
the tumour itself. Malignant change is recognised by thickening and the
development of discrete tumour nodules. They may ultimately grow to 5 cm
and a very irregular outline is also characteristic (Fig.
13.40a and b).
Acral-lentiginous
melanoma. These occur on the palms and soles and also include subungual
melanomas (Fig. 13.41). They are the most common type of melanoma found in
Japan. They carry a poor prognosis similar to nodular melanoma.
Amelanotic.
In this form, the lesion may be pink but usually close inspection will reveal
some pigmentation at the base (Fig. 13.42). Amelanotic melanoma seem to carry an
even worse prognosis than nodular pigmented melanoma. They may often present
with regional lymph node metastases.
Clinical
recognition
Malignant melanoma is almost unknown before puberty. The development of
a malignancy in a mole should be suspected if any of the following changes
occur:
Major signs
Minor signs
Change in size
Inflammation
Change in shape
Crusting or bleeding
Change in colour
Sensory change, e.g. itch
Diameter 5 mm or more
Suspicious
lesions should be removed completely with a 2 mm margin; use of incision or
punch biopsies is deprecated since accurate histological staging is impossible,
and the treatment is dependent on the histology.
Spread
Malignant melanoma may spread by local extension, by the lymphatics or
by the bloodstream. Tumour cells may reach the regional lymph nodes by embolism
but spread by lymphatic permeation is also seen, producing local satellite (Fig.
13.43a) and/or in-transit’ deposits between the primary growth and the
regional nodes (Fig. 13.43b) resulting in secondary lymphoedema. Blood-borne
metastases are seen in the lungs, liver, brain, skin and rarely in the bones.
They may also involve unusual sites, e.g. the small intestine, heart and
breasts. Secondary deposits are typically black, but
Staging
Using the American
Joint Committee on Cancer/International Union Against Cancer (AJCC/UICC)
staging system is recommended (Table 13.1).
Treatment
This is primarily
surgical.
•
There should be complete surgical excision.
•
Minimum margin of 1.0 cm and a maximum of 2.0 cm should be made. This
represents the clinical margins at surgery and not histopathological margins.
• Wide excision was advocated first by Handley in 1907 based on his
pathological studies of the frequency of centrifugal dermal lymphatic
permeation into the surrounding skin. Surgeons recommended a 5-cm margin of
excision around primary malignant melanomas; this is no longer advocated.
• Do not excise beyond the deep fascia.
• Margins may have to be altered for cosmetic or functional reasons,
e.g. periorbital region.
Survival
from primary melanoma management falls with increasing tumour thickness (Table
13.2).
Treatment
of lymph nodes
Lymph node biopsy. Fine-needle aspiration cytology (FNAC) is preferable
to excision biopsy. Open biopsy may increase
Elective
node dissection. This is not recommended for the large majority of patients. A
report of satellitosis or lymphatic invasion should warrant consideration of
node dissection. Clinically involved nodes require therapeutic node dissection.
Therapeutic
dissection for clinically positive nodes requires radical clearance by those
with expertise in the surgery of this condition. Limited dissection or ‘node
picking’ is not acceptable. Adequate clearance gives a good prognosis with a
10-year survival of 50 per cent when one node is involved. However, with more
nodes involved or extranodal spread the survival rates decrease and radiotherapy
may be considered. Groin dissections may be complicated by the development of
lymphoedema.
Lymphatic
mapping and sentinel node biopsy is a technique initially described by
Cabannas in 1974 for penile carcinoma and popularised by Morton in 1994 for melanoma.
This may provide an approach to identify those patients who may be appropriate
for elective lymph node dissection by detecting the presence of micrometastases
in the sentinel node. This technique identifies the first echelon nodes
(‘sentinel node’) using lymphoscintography following an intradermal
injection of radioactive colloid around the primary site. The position of these
nodes is marked on the skin and identified intraoperatively by injecting patent
blue dye around the site of the primary and using a hand-held gamma probe to
help to identify the position of these nodes. This accurately indicates the
presence or absence of micrometastases in a nodal field.
Loco-regional
recurrent melanoma
Loco-regional recurrent melanoma involving skin and soft tissues when
isolated should be treated surgically. Patients with multiple local or
in-transit recurrences should be considered for specialist treatment with
isolation perfusion with high-dose cytotoxic agents (Fig.
13.44). Carbon dioxide
laser ablation may be used for multiple small cutaneous lesions; or surgical
resection for isolated pulmonary, cerebral, intestinal and intraperitoneal
recurrences. In some patients it is advisable not to resect subsequent cutaneous
metastases as they can be used as an indicator of response to systemic therapies
or monitoring that of new local treatments.
Melanoma
in childhood
Melanoma in childhood is rare; however, the clinical behaviour is
similar to that in adults. The differential diagnosis is of the pigmented
Spitz naevus (juvenile melanoma) which has previously been confused as a
melanoma. This is a variant of the compound naevus in childhood. In cases of
malignant melanoma in childhood the treatment is exactly the same as that for
melanoma in adults.