While there are many forms of scarring alopecia, the common theme is a potentially permanent and irreversible destruction of hair follicles and their replacement with scar tissue.
Most forms of scarring alopecia first occur as small patches of hair loss that may expand with time. In some cases the hair loss is gradual, without noticeable symptoms, and may go unnoticed for a long time. In other instances, the hair loss is associated with severe itching, burning, and pain, and is rapidly progressive.
The scarring alopecia patches usually look a little different from alopecia areata in that the edges of the bald patches look more “ragged.” The destruction of the hair follicle occurs below the skin surface so there may not be much to actually see on the scalp skin surface other than patchy hair loss. Affected areas may be smooth and clean, or may have redness, scaling, increased or decreased pigmentation, or may have raised blisters with fluids or pus coming from the affected area.
Often, the early stages of a scarring alopecia will have inflammatory cells around the hair follicles, which, many researchers believe, induces the destruction of the hair follicles and development of scar tissue. However, there is some argument about this among dermatologists, as sometimes a biopsy from a scarring alopecia-affected individual shows very little inflammation.
Scarring alopecia almost always burns out. The bald patches stop expanding and any inflammation, itching, burning, or pain goes away. Bald areas usually have no more hair follicles. Sometimes though, hair follicles, at least those at the periphery of a bald patch, are not completely destroyed and they can regrow, but often all that is left are just a few longitudinal scars deep in the skin to show where the hair follicles once were.