Acne and Rosacea Charity Training Manual
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Follicular Hypercornification<br />
The ostium of the hair follicle or skin pore is lined with keratinocytes.<br />
Keratinocytes are the major cell of the epidermis <strong>and</strong> continually divide <strong>and</strong> as<br />
they push to the surface of the skin they mature to squames or dead skin cells<br />
(Figure 1), which are then shed <strong>and</strong> removed by the flow of oil. The hair follicle<br />
thus remains open allowing sebum to freely escape onto the surface of the<br />
skin.<br />
In acne, this changes with the cells growing abnormally <strong>and</strong> accumulating<br />
within the follicle leading to the formation of a partial blockage – the<br />
microcomedone. This is the primary lesion of acne <strong>and</strong> for successful<br />
treatment it is essential to target this lesion.<br />
Figure 1- Maturation of keratinocytes from pluripotent stem cells to<br />
dead squames which are shed.<br />
The development of the microcomedone has been extensively studied <strong>and</strong> two possible mechanisms have been suggested:<br />
1. The change in the growth of the keratinocyte is due to an immunological reaction, possibly due to the local production of interleukin (IL)1. Studies looking at<br />
isolated human pilosebaceous follicles stimulated with IL1. develop follicular hypercornification.<br />
2. The growth change in keratinocytes is the result of alteration in the constituents of sebum. In rats made deficient in linoleic acid, they develop follicular<br />
hypercornification. As stated before, the oil in sebum from acne sufferers is deficient in linoleic acid.<br />
The microcomedone is a time bomb, waiting to go off, <strong>and</strong> when it does the inflammatory lesion of acne develops. They are microscopic which means that when you<br />
target them, you need to treat the whole area of affected skin not just spots that you can see. With time, the blockages become bigger <strong>and</strong> visible. If they are close to the<br />
surface, oxidation of surface lipids leads to pigmentation – the black of the blackhead. If deeper in the follicle they bulge giving rise to the closed comedone.<br />
Glossary<br />
• Interleukin (IL)1. – Interleukins are chemical produced by a variety of cells, particularly those involved in immunological reactions. IL1 is produced by a number of cells<br />
including keratinocytes when they are stimulated by an immunological reaction.
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