Almost every type of cell in the epidermis and dermis is capable of benign or malignant overgrowth but in practice tumours fall into two main groups. Benign hypertrophic malformations which are present at or soon after birth and pre-malignant or malignant changes which occur in old age.
Fine distinction of cell type can only be made by histological examination which should invariably be carried out if the diagnosis is in doubt.
The term naevus has been used to denote birthmarks of all types. This is not wholly satisfactory since pigmented moles arising from melanocytes are also called naevi but attempts to alter custom by introduction of the term hamartoma to indicate tumour like embryonic malformations have so far failed.
A line of warty overgrowth, the individual components of which are indistinguishable from virus warts, is not uncommon on the face and neck. The warty excrescences are present at birth but the child may not be brought for consultation until aged 5-10 years. The history dating back to birth and the linear arrangement of the warts serve to distinguish them from those of virus origin. Sometimes extensive sheets of warty overgrowth may extend down the limbs and occasionally the appearance of these may be delayed until puberty.
Excision is the treatment of choice as recurrence, if incompletely destroyed by diathermy, is common.
It must be realised that epidermal cells can differentiate to form glandular or hair naevi and though not as common as keratinized warty lesions, nodules formed of cells resembling sebaceous or sweat glands and even hair follicles do occur.
Cysts which arise as developmental defects of the skin are commonly seen and may be familial. They occur most frequently on the scalp, face and neck, though can appear on any part of the body. Though called sebaceous cysts in the past, they are derived from squamous epidermis and their cheesy contents is keratin and not sebum. They can be divided into Epidermoid cysts and these often have a punctum, and Pilar cysts which have no punctum and can be distinguished histologically as their lining is similar to the external root sheath of the hair follicle.
The treatment of both is surgical removal and the pilar cysts can be recognised even macroscopically by the ease with which they can be separated from the surrounding tissue.
Vascular birthmarks are the commonest abnormalities of the skin seen in infants. Some slight capillary dilatation which shows as a pink stain over the occipital region and on the forehead and eyelids is present in 25-50 per cent of infants. The majority of facial lesions fade in the first few months of life and the occipital area is hidden by hair, thus no treatment is necessary.
A more serious problem is the true port wine stain or capillary haemangioma which is present in its full extent at birth. This bright purple macular lesion may involve one or both sides of the face, or be distributed over large areas of the limbs.
Although in it self a serious cosmetic defect a port wine stain can also indicate vascular abnormalities within the skull (Sturge Weber syndrome) or arteriovenous communication in a limb which will increase the rate of growth of the bones.
Port wine stains do not disappear spontaneously and later in life nodular vascular excrescences develop. There is no curative treatment but cosmetic creams designed to cover blemishes are now remarkably effective in disguising the disability and should be used when the child becomes aware of the social disadvantage of the disfigurement.
The strawberry mark, so called because it looks like one, has an entirely different natural history from the port wine stain. Absent or present only as a minute red dot at birth it appears when the baby is 2—3 weeks old. Growth may be rapid and alarming until 6 months when it slows down, ceasing finally at a year. By this time, the tumour is raised and bright red but blanches on pressure. Ulceration occurs in large lesions and in those on the napkin area exposed to friction and moisture. Mothers are always frightened of haemorrhage but this is exceptional and can be controlled by pressure. Spontaneous involution is the rule and this begins at 6—12 months and continues until the age of 8 years.
Ninety per cent of strawberry angiomata disappear entirely without treatment. The remaining 10 per cent leave minimal scars or capillary dilatation and some plastic repair may be required in 1 or 2 per cent. It has been our practice to leave these haemangiomata untreated. Carefully controlled trials have demonstrated that radiotherapy has no higher percentage of success and as it adds an additional hazard it can be withheld. All other methods such as freezing or the injection of sclerosing solutions, diathermy and surgery leave more scar than does natural resolution. The doctor is under great parental pressure to do something but this should be resisted and photographs which show resolution in other cases are a great help in this.
The only indication for active treatment is if the angioma interferes with respiration by pressure on the trachea. This rare complication can be controlled by systemic prednisolone. It is also possible that topical powerful corticosteroids could accelerate resolution but as yet no controlled trial has been done.
Some angiomata are entirely subcutaneous and appear only as bluish compressible swellings. The natural history of these is not as satisfactory as in the mixed type and if resolution does not occur surgery may be required.
One or more vascular spiders characterised by a central papule with radiating capillaries may appear on the face in children aged between 5 and 10 years. They are without significance and can be removed by destruction of the central vessel by diathermy or cautery.
In adults, multiple spider angiomata may develop in pregnancy and liver disease or in the genetic disorder associated with a tendency to bleeding, hereditary haemorrhagic telangiectasia. In a large proportion of people past middle age multiple bright angiomata (Campbell de Morgan’s spots) appear on the trunk. They are without any significance and do not require treatment. In the very elderly, acquired angiomata may appear on the red margin of the lip. These, if troublesome and unsightly can be destroyed by diathermy.
Pyogenic granuloma (Granuloma telangiectaticum)
A friable vascular mass of granulation tissue may arise after trivial injury such as a prick with a rose thorn or cut. Common sites are the scalp and the fingers. Distinction between this condition and an angioma may be difficult, since histologically the pyogenic granuloma consists only of new capillaries and fibroblasts. Curettage and cauterisation with electrocautery or silver nitrate is usually successful, though recurrence is possible.
Pigmented moles are formed from melanocytes, pigment producing cells situated in the epidermis and derived embryoiogically from the neural crest.
Though occasionally a cause of serious cosmetic disability, the importance of pigmented moles to the physician is the possibility of malignant change in the melanocytes. It should be appreciated that this risk is not great as the average individual has 15 to 20 moles yet the incidence of malignant melanoma is only 1-8 per 100,000 of the population per annum. This indicates little more than one mole in a million becoming malignant each year. The incidence is a little higher on exposed parts of the skin and in sunny parts of the world.
Pigmented moles are usually not present at birth but evolve during the years of childhood and even in adult life.
Proliferation of melanocytes starts first in the basal layer of the epidermis at the junction of the epidermis and dermis. At this stage the cells are actively producing melanin and are DOPA positive. As time goes by, the junction cells drop down into the dermis and become smaller, less active and DOPA negative. Normally, as moles mature, the melanocytes become entirely intradermal and all junctional activity ceases. The cessation of junctional activity occurs about puberty and, after this time, is an indication of instability of the cells and a forerunner of malignant change.
Although most malignant melanomata arise from a pre-existing mole not all do so, nor are all of them pigmented. Certain generalisations about melanomata can be made.
(i) Pigmented moles rarely become malignant until after puberty.
(ii) Hairy moles are usually safe and this applies even when they enlarge as many do, particularly in menopausal women. The only exceptions are large hairy moles which cover 20-30 per cent of the body surface.
(iii) The most dangerous moles are the smooth, slightly raised dark brown or slatish coloured lesions less than 2 cm in diameter.
(iv) As far as site is concerned pigmented naevi under nails, on the palms, soles, digits and on the mucous membranes are those that are most easily missed when they become malignant. A particular trap is the diagnosis of a subungual or melanotic whitlow. Beware of a paronychia which persists.
As with other malignant neoplams of the skin, exposure to sunlight increases the incidence, and for instance, malignant melanoma is far more common in North than in South Australia.
Any change from the normal appearance is an indication for excision and histological examination. Malignancy should be suspected when a mole shows:
(a) Increased size.
(b) Increased depth of pigmentation and its extension into the surrounding skin.
(c) Crust formation or bleeding.
(d) An inflammatory areolar around the mole.
Pigmented lesions which are frequently mistaken for melanomata are seborrhoeic warts which may be very black, pigmented basal-celled epitheliomata, histiocytomata and some angiomata in which it may be difficult to differentiate the deep-blue colour from that of melanin. Folliculitis of the hairs in a simple mole can also give rise to alarm that malignant change has occurred.
Malignant melanomata can be classified in order of malignancy. The least dangerous is the senile freckle or malignant lentigo. This occurs as a dirty grey-black discoloration on the face of the elderly. Slow extension of the impalpable pigment change continues over many years. After 10-40 years a melanoma will arise in this condition which histologically is a junctional naevus. Excision is the treatment of choice but the decision as to whether to submit an elderly patient to extensive plastic surgery can be a difficult one.
True malignant melanomata can then be divided into the superficial spreading and the nodular types, the latter most invasive of all.
Treatment. The legend that to tamper with a mole makes it malignant is not true. Moles can be safely excised and it must be emphasised that it is preferable to do an excision biopsy if malignant change is suspected, since lesser procedures may disseminate malignant cells.
In the treatment of a possible malignant melanoma, wide local excision down to the deep fascia is essential but amputation other than of digits is not usually necessary. It is still a matter of debate whether the regional lymph nodes should be removed at the time of the excision or shortly afterwards, or whether a policy of wait and see is preferable.
Antibodies to melanoma cells have been demonstrated but as yet therapy based on immunological methods has not been proven successful.
A bluish pigmentation in the sacral region is seen as a congenital abnormality in the coloured races. The pigment is formed by melanocytes in the dermis. Similar dermal pigmentation is responsible for blae naevi which may occur in the white races on any part of the body. They are much less common than the usual pigmented moles, from which they can be distinguished by their blue colour.
A not uncommon nodule in the skin of the middle aged, particularly women, is a fibrous lesion which, if examined early in its life, contains many tissue histiocytes, hence the name, and in its later stages becomes a hard fibroma. These benign tumours arise after trivial injury such as insect bites and occur most frequently on the legs. In their early stages they may be quite erythematous, firm dermal nodules, 2—3 mm in diameter and with a considerable degree of pigmentation which raises the possibility of confusion with a melanoma. Sometimes they are tender on pressure and the differential diagnosis then includes two other painful skin nodules, glomus tumour and leiomyoma. Only biopsy will give the answer. The only satisfactory treatment is excision which is needed both for diagnosis and treatment of all three conditions.
Subungual osteoma or chondroma
Another painful nodule occurs beneath toenails, usually the great toes. Frequently mistaken for a wart the surface is hard and a radiograph shows that there is a bony outgrowth from the terminal phalanx which is pushing up the nail. The treatment is surgical removal of the outgrowth.
Mucous degeneration or cyst of the extensor tendon of the finger
This nodule often miscalled a synovial cyst develops in the extensor tendon of the fingers of the aged especially those who are liable to Heberden’s nodes. It contains fluid similar to synovial fluid and may rupture, and if near the nail beds may cause a groove in the nail plate. Injection of triamcinolone around the swelling is successful in some cases though recurrences occur.
A condition which simulates a tumour but which is a degenerative disorder of the dermal collagen is granuloma annulare. This occurs mainly on the fingers and toes, is painless but worries patients because it may show no sign of resolution over a period of years. It starts with a single nodule which enlarges to form into a ring giving rise to its name. It is unrelated to generalised collagen disease but when multiple and in an adult can be associated with diabetes. It can best be treated by intralesional injections of hydrocortisone or triamcinolone.
Another dermal fibrous tumour is a keloid. This occurs mostly after injury to the skin, particularly burns, though in some people they arise spontaneously. Dense young fibrous tissue forms in scars which are particularly prone to occur in the coloured races. The diagnosis is simple when the characteristic claw-like formation occurs. Treatment is not easy since excision of a keloid is followed frequently by recurrence. Spontaneous resolution of many of the keloidal thickened scars after burns is to be expected, but resolution may be hastened by injecting them with corticosteroids which we have found reasonably effective whereas x-rays therapy is not. The steroid may also be applied in the form of adhesive tape (Haelan tape).
Changes of age
There are distinct differences in the ageing of skin dependent on whether it is normally exposed or covered by clothing. The collagen in skin exposed to sunlight undergoes atrophy and becomes yellow in colour, and at the same time the elastic fibres are damaged, a condition termed senile or solar elastosis. Thus the faces of the elderly become yellow and wrinkled. The hands and forearms show senile purpura and stellate scars with increased irregular pigmentation.
Senile comedones. Monster blackheads appear or the eyelids and around the nose coincident with collagen atrophy. They are a creamy yellow in colour and 1—5 mm in diameter but have a punctum like an ordinary blackhead. Frequently they are mistaken for xanthomata and even skin tumours. They can be removed easily by curettage.
Senile (solar) keratosis
Firm, dry, adherent scales with surrounding erythema and patchy pigmentation appear also on skin which has been exposed to sunlight for many years. Such keratoses appear in this country on the face and hands in the 65—75 years old, a little younger in fair skinned who have worked out of doors. In more sunny parts of the world similar keratoses, known then as solar keratoses, arise soon after thirty years of age. Histologically the epidermis shows irregular atrophy and hypertrophy with nuclear abnormalities, a pre-malignant picture. A small number of senile keratoses develop a neoplastic change and squamous celled epithelioma may result. Further exposure to strong sunlight should be prevented and treatment of the keratoses with 5 fluoroacil ointment is usually successful.
Another effect of exposure of the pinna to the elements is the formation of extremely tender nodules which are sufficiently painful often to interfere with sleep. Confined almost always to men who work out of doors the lesion is a result of fragmentation of the cartilage, a spicule of which penetrates the skin. Excision of the inflamed skin together with a small piece of underlying cartilage is the treatment of choice and histological examination will exclude an epitheliomatous change which can present in this way.
Seborrhoeic wart or seborrhoeic keratosis
These usually multiple lesions develop on the covered parts of the body after the age of 50. The first abnormality seen is a pale yellow or brown, slightly elevated papule with a soapy feel. Later the lesion becomes more raised with a brownish black warty surface and appears to be stuck on rather than in the skin. Some seborrhoeic warts become so dry and black that, especially on the face, they may be mistaken for melanomas. Crops of seborrhoeic warts often follow an inflammatory lesion of the skin on the trunk such as a widespread dermatitis. Often associated with the warts are pedunculated skin tags which arise on the neck and in the axillae. Seborrhoeic warts are usually symptomless, not pre-malignant and can be left untreated but, if cosmetically desirable, they can be removed by simple curettage under local anaesthesia, followed by the application of cautery or silver nitrate stick or by freezing for 30 seconds with a pencil of CO2 snow. Skin tags on the neck can be very unsightly but may be readily removed by diathermy or snipped off with scissors.
Leucoplakia can be looked on as the mucous membrane equivalent of senile keratoses. It may arise from exposure to sunlight on the lips but is usually a result of chronic irritation in the mouth from jagged teeth and smoking. Syphilis, though a rarity, should be considered if the tongue only is affected. In the mouth, leucoplakia has to be distinguished from lichen planus, a much more common cause of white thickening of the mucosa and epithelial naevi which are usually present early in life. Biopsy may have to be performed to establish the diagnosis. As has already been mentioned, leucoplakia may occur on the vulva where again histological examination may be necessary to confirm the diagnosis. As in keratoses on the skin, leucoplakia is a pre-cancerous change and, once diagnosed, regular observation is vital if it is not possible to remove the diseased area by excision or diathermy.
Basal celled epithelioma (Rodent ulcer)
The slow growing pearly nodule which is the usual variety of basal celled epithelioma in the commonest of invasive skin tumours. Occasionally, basal celled epitheliomas arise in childhood and early adult life, but the great majority appear after the age of 50. As with senile keratoses, sunlight is partly responsible and the incidence is high in the fair skinned and low in the coloured races. Seventy-five per cent of basal celled epitheliomas occur on the face and neck but the remainder arise on any part of the body, even the hands and feet.
Basal celled epithelioma should be suspected if the patient complains of a superficial crusted ulcer which has not healed over a period of some months. Often there is a history of trauma, a shaving cut, a bum or a scratch. Because the tumour arises from overgrowth of the basal cells which do not have the ability to form keratin the early nodule is smooth, translucent and without a warty surface. Growth is slow and 1 cm diameter after 5 years is not unusual.
As the nodule enlarges, a depression forms in the centre and a translucent rolled edge with telangiectases streaming over it becomes visible. This may be made more evident by stretching the skin. Pigmentation may be so marked that a melanoma is suspected. Ulceration occurs late in slow growing tumours which can appear as solid masses, for this reason rodent ulcer is a poor descriptive term. Nevertheless, basal celled tumours are locally invasive and will penetrate deeper tissues including cartilage and bone. Death from sepsis follows penetration of the skull or orbit. Metastases are a possible but rare occurrence.
The response of the surrounding tissues to the tumour cells is occasionally intense and a firm, fibrous reaction may strangle the tumour cells. The appearance then resembles a scar or pitch of scleroderma and the correct diagnosis may not be made because of the misleading history that the lesion was ulcerated but has healed. Basal celled epitheliomas are commonly multiple and may occur in considerable numbers on the trunk where their appearance resembles most closely that of intra epithelial carcinomas (Bowen’s disease). They may also be mistaken for the lesions of psoriasis, but close inspection after stretching the skin will reveal the raised pearly margin.
Treatment. The prognosis of basal celled epithelioma, if treated early, is excellent, in the region of 98 per cent clinical cure should be obtained. It is therefore important that a correct diagnosis should be reached as soon as possible. It is essential to carry out a biopsy if a clinical diagnosis cannot be reached. For small basal celled lesions, excision is the treatment of choice, since tissue is obtained for histology and the whole tumour is removed. Larger lesions may be treated successfully by a number of methods and the decision which to use must depend on the availability of the method and the preference of the clinician. External irradiation by x-rays with fractionated techniques is still a most widely used method and is successful even where there is poor blood supply such as over cartilage. In recent years, curettage and cautery has risen in popularity. This method has the advantage of speed and can be done without transporting patients to hospital. The antimitotic drug 5 fluorouracil is not as successful in the treatment of rodent ulcers as it is for keratoses. It has a place in the treatment of the very elderly who refuse more active measures but not as routine therapy. For recurrent and large neglected lesions complete removal of the tumour and reconstruction by plastic surgery may be necessary.
This tumour is not as common as basal celled growths but affects the same areas of the body, mainly the central face and the backs of the hands. It arises by the rapid proliferation of squamous epidermal cells, possibly from the hair follicles. Similar tumours have been produced experimentally in animals and birds by application of carcinogens which initiate growth most rapidly in the resting hair follicles. As in other malignant skin tumours, excessive exposure to sunlight increases incidence. The striking feature of keratoacanthomata is that the tumours grow very rapidly and then, after several weeks, involute spontaneously.
The tumour starts as a firm, skin coloured or red papule which grows very speedily attaining a size of 2 cm diameter in 3 to 6 weeks. As it reaches full size, the centre of the dome-shaped nodule becomes filled with a firm keratin plug and resembles a giant molluscum contagiosum lesion. The sides of the nodule are white or skin coloured with fine telangiectatic blood vessels running over them and in this way resembles a rodent ulcer. The speed of growth of the ketatoacanthomata should help to distinguish them. After several weeks the lesion shrinks. The central keratin plug separates and a crater is revealed which ultimately leaves a depressed scar with a crenelated edge. Keratoacanthomata may be multiple and sometimes appear in large numbers. Both microscopically and macroscopically it may be impossible to distinguish keratoacanthomata from a well differentiated squamous epithelioma and the most helpful diagnostic feature is the extremely rapid growth of the keratoacanthoma.
Treatment. Keratoacanthoma should be treated as natural resolution leaves an ugly scar and histological examination is essential to exclude a squamous epithelioma. A small biopsy comparable to a slice of cake should be taken and the remainer of the lesion can be removed by curettage, the bleeding being controlled by cauterisation. Patients should be observed until the lesion has healed as recurrences do arise.
True squamous epithelioma usually arises in skin which has become ‘unstable’ as a result of chronic inflammation. Thus it is to be suspected when a heaped up nodule arises in a senile keratosis, a scarred patch of lupus or on the vulva or lip which is the site of leucoplakia. The tumour arises from the prickle cells of the epidermis and thus can form keratin and in contrast to basal celled tumours is hard and warty. A heaped up, ulcerated cauliflower-like appearance appears at a later stage. Fortunately, most squamous epitheliomas are well differentiated and metastasise late.
The diagnosis should be confirmed by biopsy and treatment should be arranged in collaboration with surgeon and radiotherapist.
A rare, slowly progressive, malignant change confined for many years to the epidermis alone may present in a number of ways depending on the site involved. Bowen’s disease or intra-epidermal carcinoma of the skin resembles a patch of chronic eczema or psoriasis. The fact that the lesion has been present 10-25 years and steadily enlarges should arouse suspicion that it is not a simple skin reaction. A true metastasing squamous change takes place when the neoplastic cells burst through the basal layer so a sudden acceleration of the lesion is to be expected. Comparable persistent inflammatory patches can occur on the glans penis (erythroplasia) and vulva. Paget’s disease of the nipple is a similar disorder which arises in association with a duct carcinoma of the underlying breast. A unilateral chronic eczema of the nipple and its areola should always be suspect. Final diagnosis of all these conditions will depend on histological examination.
Treatment of Bowen’s disease and erythroplasia is by excision, radiotherapy or freezing with carbon dioxide snow: locally applied antimitotic drugs have proved more effective in this condition than in most other neoplasms of the skin. Amputation of the breast is the treatment for Paget’s disease of the nipple.
Few of the tumour cells which can be demonstrated in the peripheral blood arising from systemic carcinoma give rise to secondary deposits in the skin, but it should be appreciated that nodular growths in the skin may not always be primary tumours of the skin itself but secondary deposits from an internal organ. The correct diagnosis of a solitary nodule is unlikely to be made without histological examination.