Conditions to consider in the differential diagnosis of perifolliculitis capitis abscedens et suffodiens (PCAS) include the following:
Acne keloidalis nuchae
Tinea capitis 
Alopecic and aseptic nodules of the scalp (AANS) is another disorder to consider in the differential diagnosis. According to a study by Abdennader et al, however, characteristics of AANS, including the occurrence of nonscarring alopecia, differentiate it from PCAS.