Acne vulgaris is an inflammatory condition of which skin structure?

• A. Pilosebaceous unit
• B. Sebaceous gland
• C. Hair follicle
• D. Dermis

Answer: (A)

Acne vulgaris centers on the pilosebaceous unit—the hair follicle together with its attached sebaceous gland. In acne, the follicular opening (infundibulum) becomes clogged by excess keratin and sebum, creating a plugged pore. Propionibacterium acnes (Cutibacterium acnes) can then proliferate within this closed environment, triggering an inflammatory response that leads to papules, pustules, and sometimes nodules. The sebaceous gland is part of this unit, but the inflammatory process is organized around the entire pilosebaceous structure, not just the gland alone. The dermis is deeper tissue where inflammation may extend, but the origin and key pathology occur in the hair follicle–sebaceous gland complex.