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.
A blood blister is a specific blister that is formed when blood vessels beneath the skin are ruptured, but the surface of the skin isnât actually broken.d. The most common cause of a blood blister is a trauma in which the skin is pinched in something, often something like a pair of scissors or pliers, or the hinge of a door or some other object. The blood vessels are therefore ruptured, but in the absence of a pulling or cutting wound, the skin itself is not breached.