What is Folliculitis Decalvans? Folliculitis Decalvans is a rare form of Scarring Alopecia characterized by chronic inflammation of the hair follicles. It presents as red, swollen and pustular lesions on the scalp, often accompanied by itching and pain. As the condition progresses, the inflammatory lesions lead to permanent hair loss and scarring. The exact cause of Folliculitis Decalvans remains unclear, but it's believed to involve a combination of genetic predisposition and bacterial infection.