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.
The only time a wound should be covered is if itâs bleeding, oozing, or infected. Otherwise, you just have to keep the scab clean and dry. Scabs donât work unless they are dry. When scabs get wet, they begin to fall apart and tear, which allows bacteria to get in and cause major problems.