Acne and Rosacea Charity Training Manual

Acne – Clinical
The clinical lesions of acne can be divided into non-inflammatory and inflammatory. All clinical lesions arise from the micro-comedone, which is the primary
lesion of acne (see Module 1).
Non-inflammatory lesions of acne
Micro-comedones, as the name suggests are microscopic and are not clinically visible. These develop into open comedones – blackheads (Figure 1a), and
closed comedones – white heads (Figure 1b). In these lesions, the follicular cornification restricts oil flow to the surface with accumulation of sebum in the
follicle solidifies and gives rise to the toothpaste like substance that you squeeze out with blackheads. Blockage of the skin pore is compounded by the
formation of biofilm by P acnes.
Figure 1a - Open Comedones
Figure 1b - Mainly Closed Comedones and Papules
Glossary
• Biofilm – a matrix of extracellular polymeric substance produced by P acnes which sticks the bacteria together and to the follicular wall.