Acne vulgaris


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Acne vulgaris

Integumentary system

Pigmented skin disorders



Acneiform skin disorders

Acne vulgaris



Hidradenitis suppurativa

Papulosquamous and inflammatory skin disorders

Contact dermatitis

Atopic dermatitis

Lichen planus

Pityriasis rosea


Seborrhoeic dermatitis


Keratotic skin disorders

Actinic keratosis

Vesiculobullous skin disorders

Epidermolysis bullosa

Bullous pemphigoid

Pemphigus vulgaris

Desquamating skin disorders

Erythema multiforme

Stevens-Johnson syndrome

Skin integrity disorders

Pressure ulcer




Skin infections




Necrotizing fasciitis

Human papillomavirus

Varicella zoster virus

Poxvirus (Smallpox and Molluscum contagiosum)


Herpes simplex virus


Malassezia (Tinea versicolor and Seborrhoeic dermatitis)

Pediculus humanus and Phthirus pubis (Lice)

Sarcoptes scabiei (Scabies)

Human herpesvirus 6 (Roseola)

Parvovirus B19

Varicella zoster virus

Measles virus

Rubella virus

Skin neoplasms

Vascular tumors

Human herpesvirus 8 (Kaposi sarcoma)


Skin cancer

Hair and nail disorders

Alopecia areata

Telogen effluvium


Integumentary system pathology review

Pigmentation skin disorders: Pathology review

Acneiform skin disorders: Pathology review

Papulosquamous and inflammatory skin disorders: Pathology review

Vesiculobullous and desquamating skin disorders: Pathology review

Skin cancer: Pathology review

Bacterial and viral skin infections: Pathology review

Viral exanthems of childhood: Pathology review


Acne vulgaris


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High Yield Notes

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Acne vulgaris

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Content Reviewers

Rishi Desai, MD, MPH


Cassandra Bankson

Sam Gillespie, BSc

Jake Ryan

Kara Lukasiewicz, PhD, MScBMC

Tanner Marshall, MS

Samantha McBundy, MFA, CMI

With acne vulgaris, acne means “eruption” and vulgaris, means “common”. So acne vulgaris is a common skin eruption that occurs when hair follicles, or pores, get blocked by particles like dead skin cells or oil. Once hair follicles are blocked, it forms small raised, red bumps on the skin. Acne is particularly common among teenagers because of the skin changes that occur during puberty. Acne can be categorized into different types based on specific characteristics. For example, mild acne usually consists of whiteheads and blackheads, moderate acne, usually consists of pustules, and severe acne, usually consists of cysts and nodules.

Now, the skin is divided into three main layers--the epidermis, dermis, and hypodermis. The epidermis forms the thin outermost layer of skin, and has 5 sublayers: the stratum corneum as the outermost layer followed by the stratum granulosum, the stratum spinosum, and the stratum basale. In the palms and feet, which are areas with thicker skin, there is a fifth layer called the stratum lucidum which is around one cell layer thick. Underneath the layers of the epidermis is the dermis, and it’s mainly made up of connective tissue but also contains nerve endings, hair follicles, sweat glands, sebaceous glands, lymphatic vessels and blood vessels. Focusing on the hair follicles, each one contains a strand of hair, composed of the shaft, root, and bulb that sits in the follicle. The hair follicle is epidermal tissue that dips down into the dermis, and is associated with other structures like apocrine glands, sebaceous glands, the arrector pili muscle, and nerve receptors. Now, sebaceous glands, or oil glands, are located in the dermis layer of the skin and are connected to hair follicles. Each sebaceous glands secrete an oily substance called sebum into a nearby hair follicle or through pores that extend directly to the skin surface. Sebum is a substance made of different fatty acids and waxy esters to help transport nutrients and lubricate the skin. As it turns out, arrector pili muscles surround the sebaceous glands, so when these tiny muscles contract, sebum gets squeezed out. Sebum softens the hair shaft preventing it from becoming brittle. Sebum also prevents moisture loss from the skin and is slightly acidic, which helps to deter pathogens. And below all of this is the hypodermis which is made of fat and connective tissue that anchors the skin to the underlying muscle.


Acne vulgaris (commonly called acne) is a chronic skin disease that occurs when hair follicles are clogged with dead skin cells and oil from the skin. It is characterized by blackheads or whiteheads, pimples, oily skin, and possible scarring.

It primarily affects areas of the skin with a high number of oil glands, such as the face, chest, shoulders, and back. Acne is self-limiting but can cause significant emotional distress.


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  2. "Harrison's Principles of Internal Medicine, Twentieth Edition (Vol.1 & Vol.2)" McGraw-Hill Education / Medical (2018)
  3. "Pathophysiology of Disease: An Introduction to Clinical Medicine 8E" McGraw-Hill Education / Medical (2018)
  4. "CURRENT Medical Diagnosis and Treatment 2020" McGraw-Hill Education / Medical (2019)
  5. "Acne vulgaris" BMJ (2013)
  6. "Epidemiology of acne vulgaris" British Journal of Dermatology (2013)
  7. "Pathways to inflammation: acne pathophysiology" European Journal of Dermatology (2011)

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