Predisposing factors for skin cancer are
Ref Robbins 9/e p1155; Harrison 16/e p497 Uvrays and chronic ulcer are also the answers proliferation. Dysplasia is encountered principally in epi- thelial lesions. It is a loss in the uniformity of individual cells and in their architectural orientation. Dysplastic cells exhibit considerable pleomorphism and often possess hyperchro- matic nuclei that are abnormally large for the size of the cell. Mitotic figures are more abundant than usual and frequently appear in abnormal locations within the epithe- lium. In dysplastic stratified squamous epithelium, mitoses are not confined to the basal layers, where they normally occur, but may be seen at all levels and even in surface cells. There is considerable architectural anarchy. For example, the usual progressive maturation of tall cells in the basal layer to flattened squames on the surface may be lost and replaced by a disordered scrambling of dark basal- appearing cells (Fig. 5-6). When dysplastic changes are marked and involve the entire thickness of the epithelium, the lesion is referred to as carcinoma in situ, a preinvasive stage of cancer (Chapter 18). Although dysplastic changes often are found adjacent to foci of malignant transforma- tion, and long-term studies of cigarette smokers show that epithelial dysplasia almost invariably antedates the appear- ance of cancer, the term dysplasia is not synonymous with cancer; mild to moderate dysplasias that do not involve the entire thickness of the epithelium sometimes regress completely, par- ticularly if inciting causes are removed. Clinical Features Although most of these lesions arise in the skin, they also may involve the oral and anogenital mucosal surfaces, the esophagus, the meninges, and the eye. The following com- ments apply to cutaneous melanomas. Melanoma of the skin usually is asymptomatic, although pruritus may be an early manifestation. The most impoant clinical sign is a change in the color or size of a pigmented lesion. The main clinical warning signs are 1. Rapid enlargement of a preexisting nevus 2. Itching or pain in a lesion 3. Development of a new pigmented lesion during adult life 4. Irregularity of the borders of a pigmented lesion 5. Variegation of color within a pigmented lesion These principles are expressed in the so-called ABCs of melanoma: asymmetry, border, color, diameter, and evolu- tion (change of an existing nevus). It is vitally impoant to recognize melanomas and intervene as rapidly as pos- sible. The vast majority of superficial lesions are curable surgically, while metastatic melanoma has a very poor prognosis. The probability of metastasis is predicted by measuring the depth of invasion in millimeters of the veical growth phase nodule from the top of the granular cell layer of the overlying epidermis (Breslow thickness). Metastasis risk also is increased in tumors with a high mitotic rate and in those that fail to induce a local immune response. When metastases occur, they involve not only regional lymph nodes but also liver, lungs, brain, and viually any other site that can be seeded hematogenously. Sentinel lymph node biopsy (of the first draining node of a primary melanoma) at the time of surgery provides additional information on biologic aggressiveness. In some cases, metastases may appear for the first time many years after complete surgical excision of the primary tumor, suggesting a long phase of dormancy, during which time the tumor may be held in check by the host immune response. Recognition of the likely role of the host immune response has led to therapeutic trials of immunomodula- tors. Some impressive responses in patients with advanced
Smoking
Uv light
Chronic ulcer
Infrared light
General anatomy