This invasive tumour with the ability to metastasize arises from the epidermis (keratinocytes) or skin appendages. It is most commonly seen on previously damaged (e.g. by ultraviolet radiation) or chronically irritated skin. It has also been associated with certain occupations (e.g. chemical carcinogens inducing cancer of the scrotum) or with certain social customs (e.g. tumours on the legs from radiant heat from fires). Albinism and xeroderma pigmentosum may produce severe actinic damage to the skin and frank malignancy at an early age. Viral disease may predispose to squamous carcinoma and human papilloma virus may be isolated from the skin of patients with epidermodysplasia verruciformis.
Tumours are hyperkeratotic and crusted and are usually seen over sun-damaged skin, e.g. on the pinna. Induration of the tissue provides a further clue to the diagnosis. Ulceration may occur if the lesion is on sites such as the lips or genitalia. Papilliferous and more friable tumours may appear on relatively normal skin.
These occur on sun-exposed and chronically damaged skin especially in those of Celtic origin. They appear as red or brown, rough hyperkeratotic lesions on the forehead, cheeks, ears, backs of hands and on the bald or thinly covered scalp. They represent a maturation defect of keratin and are often more easily felt than seen. Superficial lesions, where the diagnosis from squamous carcinoma is clear, respond to cryotherapy with liquid nitrogen.
Bowen’s disease or intraepidermal carcinoma becomes invasive in approximately 5% of patients. When small superficial psoriasiform lesions or eczematous type lesions occur on the legs of elderly females they may persist for years and are sometimes accompanied by thickening and marked crusting or a papular component. The diagnosis should be confirmed by histology followed by excision or radiotherapy.
Treatment is usually by excision or by radiotherapy. Superficial lesions may be treated with cryosurgery.
This tumour, formed by epidermal melanocytes, is rising in incidence throughout the world. This increase has been seen particularly in light-skinned people. The latitude and length of residence of these people in places such as Australia suggest that UV light exposure is important. A single episode of severe sunburn is a significant risk factor, emphasizing the importance of occasional as opposed to constant light exposure. An increase in tumours on skin that has not until recent years been commonly exposed to sun, also indicates that exposure is a significant factor. Inheritance is also important in the dysplastic naevus syndrome, when large multiple and atypical naevi on the trunk show a familial trait and patients may develop multiple primary melanomas.
Malignant change is recognized in pre-existing naevi, especially pigmented naevi, that cover a large surface of the skin, e.g. bathing trunk naevi, and in lentigo maligna.
Lentigo maligna represents an increased number of melanocytes at the epidermodermal junction. It begins as a flat freckle-like lesion, which in time changes colour and pattern as it grows. It occurs on the facial or sun-exposed skin of patients in their sixties or older. It is a precursor of malignant melanoma. Malignant change in a mole should be suspected with a change in size, outline, colour, surface or elevation. Symptoms that include itching, bleeding after minor trauma or an increasing awareness of the tumour should also arouse suspicion.
The prognosis is directly related to the thickness of the tumour assessed at histological examination; patients with a tumour less than 1 mm thick have a 5-year survival rate of more than 90% but for tumours greater than 3.5 mm thick the 5-year survival rate is less than 50%. The prognosis is also related to the site; patients with a tumour on the trunk fair better than those with facial lesions, but worse than those with lesions on the limbs. Public health campaigns are necessary for:
• Prevention by avoiding direct sunlight and in the use of topical sunscreens
• Awareness and early diagnosis of suspected lesions by self-examination, particularly in light-skinned, blueeyed people.
Excision is performed according to the depth of invasion:
1 ern excision margin for every 1 mm of invasion with a wide excision of deeper invasive lesions followed by skin grafting. Deeply invasive lesions on a limb may be further treated by isolation and arterial perfusion with cytotoxic agents such as mustine hydrochloride. Radiotherapy, chemotherapy and immunotherapy have not yet been shown to materially alter the outlook for those with disseminated disease.
This is a lymphomatous invasion of the skin by T lymphocytes (CD4+) (see p. 133) that may eventually form cutaneous turn ours. In the final stages of the disease there is spread to lymph nodes and other organs. The name implies mushroom-like growths on the skin but these are a rare and often terminal event. In the Sezary syndrome the area of skin infiltration is greater and 10% or more atypical mononuclear cells appear in the blood. Both of these conditions are classified as aT-cell lymphoma.
The most common presentation of patients seen in the UK is with a pattern of scaling and erythema that may remain confined over areas such as the buttocks, thighs or trunk as rather fixed patches for many years. Tumours may then develop initially as plaques (Fig. 20.22) and then as ulcerating nodules or masses; dissemination follows with visceral spread and death. With an onset in middle life or old age, patients will often die from other causes. Presentation with advanced disease and spread to local lymph nodes is uncommon in the UK but has been described more frequently in the USA.
Topical mustine hydrochloride, PUV A, photophoresis or electron beam therapy may control widespread disease and plaque forms of the disease. The combination of prednisolone and chlorambucil may limit the spread of more advanced disease, but dissemination to the viscera is associated with the terminal phase of the disease. Multiple chemotherapeutic regimens are disappointing in their effect.
Kaposi’s sarcoma is a vascular, multifocal, malignant tumour. It is seen in:
• Patients with AIDS. The incidence is higher in homosexuals than in haemophiliacs.
• Immunosuppressed patients secondarily to chemotherapy.
• Elderly males of Jewish or Mediterranean origin (classic form).
• Africans: several forms are seen, namely classical, locally aggressive or lymphadenopathic.
The initial lesion appears as a bruise that gradually darkens and becomes raised as a firm nodule (Fig. 20.23). Lesions are not usually painful or itchy initially and can develop at several sites all over the body. Gastrointestinal lesions (approximately 40% of cases) are usually asymptomatic but later liver and lymph node involvement occur.
PROGNOSIS AND TREATMENT
Lesions may progess rapidly, enlarge slowly over years or even regress. Treatment is with radiotherapy or chernotherapy. In AIDS one-third of the patients may show a response but relapse later; prognosis is poor. The prognosis is slightly better in the other forms and in those on immunosuppressive drugs the lesions may regress on stopping therapy.