Which term is used for a dry, rough surface or dried exudate/blood on the skin?

The term "crust" specifically refers to a dry, rough surface that can develop on the skin due to the drying of exudate, blood, or other fluids. This crusty layer often forms as a healing response, protecting underlying tissues from infection and further injury. It is commonly seen in conditions like eczema, impetigo, and after certain injuries where fluids have exuded and subsequently dried on the surface.

Other terms, while related to skin conditions, refer to different phenomena. An ulcer is defined as a break in the skin or mucous membrane, leading to tissue loss and potential infection. A pustule is a small elevation on the skin filled with pus, often indicating localized inflammation or infection. A fissure, on the other hand, refers to a linear crack or split in the skin, usually occurring in areas prone to dryness or tension, rather than a dried or crusty surface. Each of these terms addresses specific types of modifications or lesions of the skin, distinguishing them from the concept of a crust.