Skin discoloration on lip. What does cancer look like?

Non-healing ulcer. While discoloration may be one symptom of an early lesion or a pre-cancerous lesion, lip cancers usually present as non-healing ulcers. It would be prudent to consult your doctor if you have any doubt.
Lip cancer. Cancer on the lip may present like a discoloration. Lip cancer may also present as a lump, or an ulcerative lesion. Squamous cell carcinomas and basal cell carcinomas can commonly occur, but there are other types too.