Secondary skin lesions

Primary against secondary

Describing a skin lesion starts by putting it in one of two groups. A primary lesion is the early stage of the lesion, how it looks when it starts, prior to evolving. A secondary lesion is the later stage, after the lesion has evolved or been altered by external factors, scratching for example. So the question is not what the lesion is made of but how far along it is.

The six named secondary lesions, and atrophy with them

The six named together are crust, scale, excoriation, fissure, erosion and lichenification, and atrophy is defined alongside them:

• Crust: dried fluid and blood and dead cells arising from broken vesicles and bullae.
• Scale: plates that represent desquamated layers of stratum corneum.
• Erosion: partial loss of the epidermis.
• Excoriations: abraded skin caused by scratching or rubbing.
• Fissure: linear cleavage of skin which extends into the dermis.
• Lichenification: a thickening of the epidermis with exaggeration of normal skin lines.
• Atrophy: thinning or absence of the epidermis, dermis or subcutaneous fat.