Malignant and premalignant tumours
Malignant and premalignant tumours
Malignant and premalignant tumours
Squamous carcinomaMore than in other skin malignancies, there is likely tobe an identifiable cause for squamouscarcinoma . The tumour often arises from apremalignant condition and is distinguished clinically byinduration of the base and surrounding normal tissues.With growth, ulceration usually occurs.Squamous carcinoma is more liable to metastasize toregional lymph nodes than is basal carcinoma, and distantmetastases can occur.Diagnosis is by biopsy. Keratoacanthoma can be difficult to distinguish both clinically andhistologically from squamous cell carcinoma.Treatment will usually be by surgical excision, althoughin some circumstances radiotherapy may be preferable.
Basal cell carcinoma Basal cell carcinoma (BCC), or rodent ulcer, arises from cells that resemble the basal layer of theepidermis, and may have its origin from skin appendageepithelium. It is the commonest malignant skin tumour inwhite skin, and although sunlight exposure is clearly amajor aetiological factor, unlike squamous cell carcinomait is not often seen on the backs of the hands. The faceis the commonest site, although when there has beenexposure to a systemic carcinogen, such as inorganicarsenic, BCC can be multiple and widespread.The tumour is usually slow-growing, evolving from atranslucent papule. Various growth patterns may occur, e.g.superficial spreading, nodular, infiltrative and sclerosing.Most nodular and infiltrative tumours ulcerate. Except forthe sclerosing variety, BCC tends to retain a translucentraised margin as it extends into surrounding tissues.Telangiectatic vessels are often visible on the surface andmay bleed on contact. In some tumours there is anadmixture of melanocytes, and the resultant lesion cansimulate malignant melanoma. Local destruction can be extreme, and very rarely BCC metastasizes.
Treatment is usually by excision, radiotherapy, curettageor cryotherapy.
Malignant melanoma Malignant melanoma usually arises either frompreviously normal-looking skin,or from a benignmelanocytic naevus. It may also arise from a naevusin a nailbed, in a mucous membrane or from the choroidor the iris.At present there is a rapidly rising incidence amongwhite people and, aetiologically, short burstsof sun exposure, as during a hot, sunny holiday, may beimportant. There is not the same association with chronicsun damage as with squamous cell carcinoma, and to alesser extent BCC. Conditions that can give rise tomelanoma are lentigo maligna (Hutchinson's freckle) anddysplastic naevus. Lentigo maligna evolves as a flat, brown,variably pigmented patch, which slowly spreads onmarkedly sun-damaged skin. Dysplastic naevi areunusual-looking, often larger than average, with a distinctivehistology; they are sporadic or inherited as an autosomaldominant characteristic, and may be a precursor tomelanoma.Melanoma is often suspected when an enlarging pigmentedlesion has one or more of the following: irregularnotched border; irregular pigmentation, often with red andwhite as well as brown/black areas; itching or pricklingsensation; inflammatory halo; ulceration and bleeding.The malignant cells spread laterally, in and just beneaththe epidermis, and inwards. The prognosis depends on thedepth of invasion, being excellent for completely excised,very superficial tumours. Metastasis occurs both toregional lymph nodes and distantly.
Lymphoma and leukaemia in the skinB-cell lymphoma, Hodgkin's disease and leukaemia mayoccasionally metastasize to the skin, or rarely present withcutaneous nodules. The skin is usually involved rather latein the course of the disease. The diagnosis is made frombiopsy and other characteristic features of these diseases.T lymphocytes have an affinity for the epidermis and itsappendages, and therefore T-cell neoplasia often involvesthe skin from the outset and may appear to be localized tothe skin in some cases.Mycosis fungoides is the best-characterized T-cellcutaneous neoplasm. There is often a long phase ofpoikilodermatous patches (poikiloderma is a combinationof erythema, atrophy and reticulate pigmentation) beforeplaques and tumours appear. Itching usuallyoccurs. Erythroderma can develop, and if there arecirculating neoplastic T cells this constitutes Sezary's syndrome.Lymphadenopathy and visceral involvement occurlate and indicate a poor prognosis.
Metastatic malignancy Nodules, often ulcerating, may occur with many visceralmalignancies
.Paget's disease of the nippleThe epidermis of the nipple becomes invaded by malignantcells arising from an underlying intraduct carcinoma of thebreast tissue. The lesion is red, crusted and well defined,like Bowen's disease.
Kaposi's sarcoma Kaposi's sarcoma probably has a viral aetiology- human herpesvirus. The lesions of this multicentricvascular neoplasm are usually purplish patches, plaques ornodules. Leakage of blood readily produces purpura andbrown staining of the skin. The lymphatics can be affected,producing lymphoedema.Initially the lesions may be insignificant-looking, flat,reddish-brown or purple patches.distinctive featureof AIDS-related Kaposi's sarcoma is a tendencyfor ovoid lesions to orientate along major skin creases,which on the trunk resembles the arrangement seen inpityriasis rosea.
Treatment, when indicated, is radiotherapy for localizedlesions and, in some cases, cytotoxic chemotherapy forextensive disease.Primary sarcomas Malignant tumours arising from the various mesenchymalelements in the skin are all rare and present as enlarging masses.
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