Melanoma occurs predominantly in adults, and more than half of the cases arise in apparently normal areas of the skin. Early signs in a nevus that would suggest malignant change include darker or variable discoloration, itching, an increase in size, or the development of satellites. Ulceration or bleeding are later signs. Melanoma in women occurs more commonly on the extremities and in men on the trunk or head and neck, but it can arise from any site on the skin surface. A biopsy, preferably by local excision, should be performed for any suspicious lesions, and the specimens should be examined by an experienced pathologist to allow for microstaging.
Prognosis is affected by clinical and histological factors and by anatomic location of the lesion.
I melanoma may be a poor prognostic histologic factor, but this is controversial. For disease clinically confined to the primary site, the greater the thickness and depth of local invasion of the melanoma, the higher the chance of lymph node metastases and the worse the prognosis. Any organ may be involved by metastases, but lungs and liver are common sites. The risk of relapse may decrease substantially over time, although late relapses are not uncommon. The prognostic implications of microscopic satellites in patients with clinical stage I melanoma.