Types of Neutrophilic Alopecia
Dissecting cellulitis is an uncommon but readily recognized chronic inflammatory disease of scalp hair follicles. It is also known as dissecting folliculitis or perifolliculitis capitis abscedens et suffodiens. It is characterized by multiple painful sometime fluid filled nodules, interconnecting sinus tracts, and draining pus over large areas of the scalp. The condition tends to be chronic and progressive, and ultimately leads to scarring and extensive hair loss.
Dissecting cellulitis is considered part of the follicular occlusion triad that also includes acne conglobata and hidradenitis suppurativa. In some patients, only the scalp hair follicles are affected. As a follicular occlusion disorder, there is a defect in normal keratin production in the hair follicles. As a result, the hair follicles become obstructed by oil (sebaceous contents) and keratin debris. Ultimately the follicles burst resulting in an intense inflammatory reaction. It has been suggested that the cause of dissecting cellulitis may involve an abnormal host response to bacteria. However, patients with dissecting cellulitis have no evidence of immune deficiency or presence of infection at other skin sites.
It is seen primarily in dark-skinned men in the second to fourth decade of life.
It frequently begins in the posterior scalp or crown although any region of the scalp may be involved. It is characterized by multiple painful sometime fluid filled nodules, interconnecting sinus tracts, and purulent drainage may be present over large areas of the scalp. The condition tends to be chronic and progressive, and ultimately leads to scarring and extensive hair loss.
Folliculitis decalvans belongs to a group of disorders called cicatricial or scarring alopecias that destroy the hair follicle, replace it with scar tissue, and eventually causes permanent hair loss. Decalvans is a term derived from the Latin meaning “making bald.” Folliculitis decalvans is further classified as a neutrophilic scarring alopecia, based upon the type of inflammation (neutrophils) seen on routine biopsies in the early stages of the disease. This condition typically starts with crops of red bumps around the base of the hair follicles, which then develop marked inflammation, pustules formation, crusting and eventually patchy hair loss.
The cause of folliculitis decalvans is unknown, however it has been speculated that the disease reflects an abnormal host response to bacteria, most commonly Staphylococcus aureus. Such organisms may act as “superantigens” and may escape detection by the host immune system. Interestingly, patients with folliculitis decalvans typically do not have evidence of bacterial infection elsewhere on the skin, nor do they have any evidence of immune deficiency.
Although extensive epidemiologic studies are not available, the incidence of folliculitis decalvans comprises about 11% of all scarring alopecia cases. Folliculitis decalvans typically occurs in young and middle-aged adults with a slight male predominance. It also occurs more frequently in African Americans compared to Caucasians. Folliculitis decalvans can be seen families, thereby supporting a genetic predisposition.
The initial lesions of folliculitis decalvans involves a red bump around the base hair follicle usually along the crown or posterior scalp. As the inflammatory process continues bright inflammation, pus formation, scaling, and crusting takes place. Patients occasionally report spontaneous bleeding and frequently complain about pain, itching, and/or burning sensations. As the disease progresses small discrete to extensive, irregularly shaped smooth scarred patches of hair loss develop.