Impetigo and eczema are common skin diseases, according to MedlinePlus. Skin cancer (the most serious form of which is melanoma), rosacea and psoriasis are also common dermatological diseases.
Bacteria cause the skin infection known as impetigo, MedlinePlus explains. The disease is most common in young children. Its symptoms include red sores on the arms, face or legs.
Eczema, or atopic dermatitis, is characterized by dry, itchy skin and rashes, says MedlinePlus. Possible indications of melanoma are moles that are asymmetrical, ragged, unevenly colored or increasing in size. Psoriasis causes scaly or swollen patches of skin, while rosacea causes redness of the face.