Elizabeth Martin and Robert Hine. Latest Edition (7 ed.) Fully revised and updated, the sixth edition of this dictionary provides comprehensive coverage of biology, biophysics, and biochemistry, as well as key terms from medicine and palaeontology.
For example, if someone scratches a mole until it bleeds, the resulting lesion, a crust, is now a secondary skin lesion. The most common secondary skin lesions include: 1  crust: a crust, or a scab, is created when dried blood forms over a scratched and irritated skin lesion. 2  ulcer: typically caused by a bacterial infection or physical trauma. 3  scale: patches of skin cells that build up and then fall off the skin.
These include: 1  Sores or skin ulcers due to chronic (long-term) backing up of blood. These sores or ulcers are painful and hard to heal. 2  Bleeding. The skin over the veins becomes thin and easily injured. 3  Superficial thrombophlebitis (throm-bo-fli-BYT-uhs), which is a blood clot that forms in a vein just below the skin.