Squamous cell carcinoma (SCC). Light micrograph (LM) of SCC cells (pink) in the oral cavity (mouth) of a cancer patient. SCC is the second most common form of skin cancer and arises from the uncontrolled proliferation of squamous cells, flattened cells in the skin and mucous membranes. Symptoms may include a large poorly-healing ulcer or a hoarse voice. Treatment is with surgery and radiotherapy. Risk factors include smoking and alcohol consumption.