Home   Chapter Home   Jobs   Conferences   Fellowships   Books



Other dermatoses

Acne vulgaris

Reviewer: Mowafak Hamodat MB.CH.B, MSc., FRCPC (see Reviewers page)
Revised: 26 August 2011, last major update July 2011
Copyright: (c) 2002-2011, PathologyOutlines.com, Inc.


● Common skin disease of seborrhea (scaly red skin), comedones (blackheads and whiteheads), papules (pinheads), pustules (pimples), nodules (large papules) and possibly scarring
● Typically affects skin with densest sebaceous follicles: face, upper chest, back; uncommon in scalp for unknown reasons


● Acne vulgaris is common acne, typically with comedones
Acne rosacea is a different disorder


● Due to hormonal variations and alterations in hair follicle maturation
● Begins with abnormal follicular keratinization with retention of keratinous material in the follicle
● Then increased sebum production
● Then appearance of gram-positive, anaerobic, diphtheroid Propionibacterium acnes
● May become inflammatory

Stages of acne

Clinical features

● Usually teenagers of either sex, but often more severe in males
● Worsens with drugs (steroids, testosterone, contraceptives), oils/tars, heavy clothing and tropical climates
● Non-inflammatory acne is due to open and closed comedones
Open comedones: small follicular papules with central, black keratin plug (due to oxidation of melanin)
Closed comedones: follicular papules with a deeper plug below the surface
● Follicles may rupture and become inflamed


● Antibiotics, isotretinoin, phototherapy (eMedicine, Clin Cosmet Investig Dermatol 2011;4:41)

Clinical description

● Diverse lesions such as comedones, papules, pustules, cysts, sinuses and scars

Clinical images

Severe lesions

Micro description

● Three major components are comedones, inflammatory lesions and scars
● Comedones (open or closed) are cyst-like cavities filled with compact mass of keratinous material and numerous bacteria
● Closed comedo has 1-2 hairs trapped in lumen and atrophic, sebaceous acini
● Open comedo has 1015 hairs in lumen, and sebaceous acini are atrophic or absent
● Epithelial lining of comedones is usually thin

Virtual slides


End of Skin-nontumor > Other dermatoses > Acne vulgaris

This information is intended for physicians and related personnel, who understand that medical information is often imperfect, and must be interpreted in the context of a patient's clinical data using reasonable medical judgment. This website should not be used as a substitute for the advice of a licensed physician.

All information on this website is protected by copyright of PathologyOutlines.com, Inc. Information from third parties may also be protected by copyright. Please contact us at copyrightPathOut@gmail.com with any questions (click here for other contact information).