The Different Types of Acne

Acne is an inflammatory disease of the hair and sebaceous gland follicle. It is very common and affects mainly teenagers. However, adults can also be affected by this condition.

Acne is manifested by the appearance of inflammatory or non-inflammatory pimples. They usually appear on the face, but can also occur on the body (back, chest, buttocks, etc.).

Acne is a complex disease with multifactorial origin. The pathophysiology of acne includes 3 key elements:

• A hypersecretion of sebum (hyperseborrhea):

  Sebum is a complex mixture of lipids synthesized by the sebaceous glands in the dermis. Normally, it is distributed evenly over the skin and provides its protection.

  In acne, there is hypersecretion of sebum (called hyperseborrhea) in the area of hair follicles and sebaceous glands. The sebum clogs the pores, which are the openings of the sebaceous glands on the surface of the skin. In this greasy environment, the acne bacterium Cutibacterium acnes (formerly Propionibacterium acnes), which feeds mainly on sebum, can multiply well. This bacterium secretes pro-inflammatory substances that cause the inflammation and pimple formation.

• Abnormal follicular keratinization:

  In acne-prone skin, there is an abnormal thickening of the epidermal cells (hyperkeratinization) that prevents the removal of sebum. This leads to blockage of the follicular canal and formation of comedones or blackheads.

• Bacterial colonization:

  As mentioned earlier, there is a bacterium responsible for acne: Cutibacterium acnes. This bacterium secretes pro-inflammatory substances that cause acne.

  Recent research has shown that an imbalance in the skin microbiota (dysbiosis) is responsible for the proliferation of Cutibacterium acnes. Through immune mechanisms, this bacterium leads to hyperkeratinization of hair and sebaceous follicles.

  Note: Since acne is multifactorial, there are several factors that favor its occurrence, such as diet, stress or the use of inappropriate cosmetic products.

Acne is a very common disease that affects both adolescents and adults. The pathophysiology of acne includes hyperseborrhea, abnormal follicular keratinization, and proliferation of Cutibacterium acnes in the hair-sebum unit.

There is not just one type of acne, but several. They include:

• Retentive acne:

  This type of acne is mainly observed in teenagers, as it is due to an overproduction of sebum. Under the influence of hormones, the sebaceous glands produce too much sebum. This clogs the openings of the hair and sebaceous follicles, forming the acne lesions. In retention acne, two types of lesions are usually observed: Microcysts (closed comedones) and blackheads (open comedones).

• Inflammatory acne:

  Usually, the inflammatory acne follows the retentive acne (therefore, it is important to act early before the inflammation). This is because the overproduction of sebum promotes the proliferation of Cutibacterium acnes, which secretes substances that promote inflammation. If the inflammation is on the surface, papules (red elevations) or pustules (pus-filled pimples) are seen. When the inflammation is deeper, very painful nodules appear, which can develop into abscesses or cysts.

There are other, rarer and more serious types of acne:

• Acne conglobata:

  Acne conglobata or nodulocystic acne is characterized by very large comedones. These comedones become inflamed very quickly (deep inflammation), causing cysts and nodules to form. This type of acne is chronic and can leave extensive scars.

• Acne fulminans (fulminant):

  This is the rarest and most severe form of acne, affecting mostly men. Unlike the other types of acne, this is an acute form of the disease. It is characterized by a large and noticeable presence of skin lesions. The distinctive feature of this type of acne is the presence of extracutaneous signs such as fever (>39 °C) or joint pain.

• ZOUBOULIS C. C. Acne and sebaceous gland function. Clinics in Dermatology (2004)

• DRÉNO B., What is new in the pathophysiology of acne, an overview (2017)