What could cause purple-brown skin lesions?

Have it evaluated.: There are many things that may cause a discoloration of the skin. Several types of inflammatory conditions of the skin, allergic reactions, and sometimes bacterial, viral or fungal infections and cancer can cause a discoloration of the skin. Insect bites can also be the cause of a rash or a discoloration of the skin. Have it evaluated by a professional and get the appropriate treatment.