This is a more severe variant of alopecia areata, distinguished by the complete loss of all scalp hair, whereas classic AA presents as discrete patches.
CCCA is a scarring alopecia that starts at the vertex and spreads outward, distinguished by signs of permanent follicular loss (shiny skin, absent pores), unlike the non-scarring nature of AA.
This is a scarring alopecia characterized by erythematous plaques with follicular plugging and atrophy, confirmed by biopsy, which is different from the smooth, non-inflamed patches of AA.
Alopecia from morphea (en coup de sabre) presents as a linear, depressed, indurated plaque on the scalp, a scarring process morphologically distinct from the round patches of AA.
Hair loss in systemic lupus is typically a diffuse, non-scarring thinning, not the well-demarcated, perfectly smooth patches of alopecia areata.
Secondary syphilis can cause a "moth-eaten" pattern of hair loss with multiple, small, irregular patches, unlike the larger, round/oval patches of classic AA.
Tinea capitis is distinguished by the presence of scale, broken hairs ("black dots"), and sometimes inflammation (kerion), all of which are absent in alopecia areata.
This is identified by a history of tight hairstyles and hair loss primarily along the frontal and temporal hairlines, with characteristic retained "fringe" hairs.
The key finding here is patches of hair of varying lengths due to compulsive pulling, with broken and twisted hairs, unlike the smooth, complete hair loss in an AA patch.
