Hello. Welcome to HCM.
If you want to know about purely skin cancer
appearance- It can be looking like anything ranging from a small to large ulcer with indurated base to a simple nodule. Any ulceration/ bleeding or increase in size of a mole is also indicative of malignancy. The best way to diagnose a skin cancer and its nature is by an accurate clinical examination and biopsy
to prove the same.
Secondly, any other tumour from the underlying soft tissue
(muscle/ bone or fascia) can protrude through the skin. In these cases, the overlying skin can be normal or stretched or can show other changes. The best approach is an FNAC and ultrasound
to trace the depth of swelling and its nature.