Inflammatory lesions in acne
Inflammatory lesions in acne (pimples or zits) include small red bumps (papules), pustules, large red bumps (nodules) and cysts (these are fluctuant nodules). They are often painful.
More images of acne ...
What is the cause of inflammatory acne?
Inflammatory acne spots usually result from rupture of the wall of the closed comedone but may arise from normal-appearing skin.
The factors contributing to inflammation are:
- Activation of the innate immune system. The cells lining the sebaceous ducts produce inflammatory mediators (IL-1a, IL-b and tumour necrosis factor).
- Bacteria Chemicals produced by Propionibacterium acnes diffuse into the surrounding skin (dermis) and active an immune reaction.
- Foreign body reaction White blood cells (macrophages and giant cells) removing the debris may cause a more severe granulomatous inflammatory reaction.
- Irritation by lipids Free fatty acids and sebum penetrate the dermis after the duct has ruptured.
- Hypersensitivity or excessive immune reaction to P. acnes Hypersensitivity to P. acnes is thought to be the cause of the severe skin condition, acne fulminans.