Acne / Pimples:

 Acne vulgaris (commonly called acne) is a common skin condition, caused by changes in the pilosebaceous units, skin structures consisting of a hair follicle and its associated sebaceous gland via androgen stimulation.

 Acne vulgaris affects the areas of skin with the densest population of sebaceous follicles; these areas include the face, the upper part of the chest, and the back. Severe acne is inflammatory, but acne can also manifest in no inflammatory forms. Acne lesions are commonly referred to as pimples, blemishes, spots, zits, or acne.

Acne is most common during adolescence, affecting more than 85% of teenagers, and frequently continues into adulthood. The cause in adolescence is generally an increase in male sex hormones, which people of both genders accrue during puberty.   

The face and upper neck are the most commonly affected, but the chest, back and shoulders may have acne as well.