Squamous cell carcinoma (SCC) is less common than BCC but more likely to spread throughout the body if not treated promptly. It often appears as a firm red lump on sun-exposed areas such as the face, scalp, arms, hands, or legs that may ulcerate if left unchecked. Treatment usually involves surgery to remove all affected tissue or topical medications like imiquimod cream or fluorouracil cream. Radiation therapy may also be used in some cases when surgery isn't possible due to advanced age or poor health status.
Cited from the Mayo Clinic & the American Academy of Dermatology