2.2 Crust

Crust.

Surface deposits of dried secretions (serum, pus or blood), usually mixed with epithelial and sometimes bacterial debris.

Color: yellow (serum, pus), brown-black (blood).

Size: several mm to cm.

May appear anywhere on body, usually localized.

May develop into erosion or ulcer.

Associated with vesicle or pustule.

When crusts become detached, the base may be dry or red and moist.

All diagnoses associated with exudation of fluids.

Exudation of serum; leakage of blood following trauma, lesion type following papule, pustule, plaque, vesicle and bulla.