Skin cancer usually does not itch. It can, of course, itch if there is super-added overlying fungal infection or other associated causes.
Skin cancer has a varied appearance, depending on the type of cancer. Common cancers of the skin include Basal Cell Carcinoma (BCC), Squamous Cell Carcinoma (SCC), and Melanoma.
BCC is the commonest type, and pictures of typical appearances are displayed at http://www.skincancer.org/basal/index.php
SCC may present as enlarging scaly plaque in the sun-exposed skin of fair skinned people.
Melanoma has the following characteristics:
B: Borders are irregular
C: Color is varied
D: Diameter more than 6 mm