differentiate from non scarring:
- 
absence of follicular openings 
- 
presence of frank scarring 
- 
presence of fibrosis on histology 
Chronic discoid lupus erythematosus
well defined patches of:
erythema
follicular plugging
scaly skin
ultimately scarring
on scalp: leads to permanent hair loss
- 
should stay out of the sun - aggravated by ultraviolet light 
- 
first line is very potent topical steroids: clobetasol 
- 
hydroxychloroquine usually next line 
Lichen palnus:
- lichen planopilaris when affects hair follicles
redness around hair follicles - perifollicular erythema
follicular plugging
Folliculitis decalvans
intense focal scalp erythema
follicular pustules and crusting
subsequent dense scarring of the scalp
Dissecting cellulitis
- related to severe acne
- purulent nodules on scalp
> localised scarring alopecia