Folliculitis is infection of which structure?

• A. Hair follicle
• B. Hair shaft
• C. Epidermal duct
• D. Sebaceous gland

Answer: (A)

Folliculitis is infection centered in the hair follicle—the tiny invagination in the skin that surrounds the hair root and often includes the associated sebaceous gland. When microbes invade this structure, inflammation and pus form around the follicle, giving the familiar small pustules you see at hair-bearing sites. The hair shaft itself is the filament that grows through the follicle, not the site of infection in this condition. The epidermal duct and sebaceous gland can be involved in other skin problems, but folliculitis specifically denotes infection of the follicle. Staphylococcus aureus is a common culprit, and you can see this pattern after shaving or in occluded skin.