infection of the sebaceous gland and the formation of pimples
Acne
Sebaceous gland
Acne is a very common problem, particularly during puberty in teenagers, and is thought to relate to an increased production of sebum due to hormonal factors. The increased production of sebum can lead to a blockage of the sebaceous gland duct. This can cause a comedo, (commonly called a "blackhead" or a "whitehead"), which can lead to infection, particularly by the bacteria "Cutibacterium acnes". 
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Sebaceous gland [SEP] Acne
Acne is a very common problem, particularly during puberty in teenagers, and is thought to relate to an increased production of sebum due to hormonal factors. The increased production of sebum can lead to a blockage of the sebaceous gland duct. This can cause a comedo, (commonly called a "blackhead" or a "whitehead"), which can lead to infection, particularly by the bacteria "Cutibacterium acnes". This can inflame the comedones, which then change into the characteristic acne lesions. "Comedones" generally occur on the areas with more sebaceous glands, particularly the face, shoulders, upper chest and back. Comedones may be "black" or "white" depending on whether the entire pilosebaceous unit, or just the sebaceous duct, is blocked.