This daily doodle focuses on Acne Vulgaris, an inflammatory condition of the pilosebaceous unit that is associated with the formation of “comedones” (plugged hair follicles).
There are two main types of comedones:
1. Closed = white head
2. Open = black head
Contrary to the common belief that black heads are black because they are filled with “dirt”, black heads are actually black because they contain melanin, a type of pigment, which turns dark as it oxidizes. White heads are white because they still have an intact layer of skin that covers the growing sebum plug.
Pathogenesis of Acne Vulgaris:
Although the precise mechanism is unknown, several pathogenic factors have been recognized:
- Abnormal folicular keratinization: Increased proliferation and decreased desquamation of keratinocytes causes blockage of the follicular opening, resulting in comedones.
- Overproduction of sebum: The sebaceous glands in acne patients seem to be larger, and produce more sebum than normal. Around puberty, there is an androgen- dependent increase of sebum production, coinciding with the onset of acne in most patients.
- Overgrowth of follicular bacteria: Propionibacterium acnes is a normal colonizer of human follicles, using sebum as a growing medium. P. anes is present in excessive numbers in patients with acne. It plays a role in the induction of inflammation and scarring.
- Other considerations: Diet does not play a definitive role in the development of acne. However, excessive consumption of milk has been associated with nodulo-cystic acne. “Acne is not caused by chocolate or fatty foods or, in fact, by any kind of food” – Quote from Fitzpatrick’s Color Atlas and Synopsis of Clinical Dermatology. Exacerbation factors include emotional stress and “acne mechanica” – occlusion/pressure on the skin (ex: leaning face on hands).
Grading acne severity:
For management purposes, acne activities fall into mild, moderate and severe groups.
• Mostly comedones
• Few inflammatory lesions
• No scars
In moderate acne
• Numerous comedones
• Numerous papules and pustules, but NO deep cysts or nodules
• Few or no macroscopic scars
In severe acne
• Comedones, cysts or nodules
• Significant scarring
• Papulo-pustular acne with significant scarring is also considered severe acne.
- Y. Zhou, “Acneiform Disorders”. UBC Second Year Lecture Notes. January, 2012
- D. Thiboutot and A. Zaenglein, “Pathogenesis, clinical manifestations, and diagnosis of acne vulgaris”. Uptodate.com. October, 2013. Link: http://www.uptodate.com/contents/pathogenesis-clinical-manifestations-and-diagnosis-of-acne-vulgaris#H3
- K. Wolff and R. Johnson, “Fitzpatrick’s Color Atlas and Synopsis of Clinical Dermatology” McGraw-Hill Companies. 2009