Which condition involves an inflammatory reaction of hair follicles resulting in red, pustular lesions?

Folliculitis is characterized by an inflammatory reaction of hair follicles, leading to the development of red, pustular lesions. This condition occurs when hair follicles become infected or irritated, typically by bacteria, leading to inflammation. The pustules are formed as a response to the infection, which can cause discomfort and tenderness in the affected areas. Folliculitis commonly appears on the scalp, face, neck, and in areas where friction occurs, such as the thighs or buttocks.

The other conditions listed are related to the skin but have different causes and manifestations. Furunculosis, for example, refers to deeper infections of hair follicles (boils) that can result from folliculitis but involves more extensive inflammation and painful, larger nodules. Acne vulgaris is primarily associated with the blockage of hair follicles by oil and dead skin cells leading to comedones, cysts, and pustules linked to hormonal changes rather than direct inflammation of follicles. Dermatitis encompasses a broad range of skin inflammatory conditions, often with a variety of additional symptoms, but does not specifically target hair follicles in the way that folliculitis does.