Hair folliculitis is an inflammatory skin disease where hair follicles get inflamed. Deep facial folliculitis usually affects the deeper part of a follicle and is characterized by redness, swelling and pus formation in the scalp. Severe infections may lead to permanent hair loss and even scarring. The inflammation that triggers this condition may affect any part of the scalp, but is more often found on the forehead, eyebrows, nose, and upper lip.
Infection of hair follicles may result in changes in the protein structures of keratin – a necessary component of hair strands – resulting in the thinning or hair loss of patients’ hair. In general, the disease occurs when keratinous (protein-based) materials called keratinocytes are washed away by sweat or tears. The process of washing away the keratinocytes alters the structure of keratin, which in turn affects how the keratinocytes are able to respond to external stimuli such as stress. As a result, the keratinocytes no longer respond to signals from the immune system to trigger hair regeneration or to produce new hair.
Hair folliculitis may manifest in various forms. Initially, there are small, imperceptible white bumps that form in response to irritating conditions like friction or intense heat from brushing or touching. These white bumps gradually grow in diameter until they almost cover the entire surface of the scalp, finally transforming into painful, thick yellow or red papules. The presence of these papules indicates that the hair follicles have been damaged.