Acne is broadly classified into types and severity which all occur at certain developmental stages of our lives with different underlining pathophysiological processes and hence requiring different treatment options.
These are primary lesions of the skin during the stages of acne progression.
Closed comedo(whiteheads).They appear as prominent coloured, discrete,epidermal clogged follicles beneath the skin surface also projecting as whitish small bumps.They are more dominant on the nose,cheeks and forehead.
Open comedo(blackheads).Their surface are usually black,flesh white or dark bumps.This results from hyperactivity of the cells lining the sebaceous ducts which may lead to eventuall obliteration of the ducts forming a comedone.The obvious black colour results from the combined action of plugs of sebum,sloughed-off cells and melanin oxidation.
Acne Papules.Papular acne are coloured or skin bumps,usually 5mm or less in diameter,solid skin-raised lesions minimally inflammatory and non-pustular, they can be painful too.A break in the follicular wall allows bacteria and cellular debris to spill into the dermis especially when a pore becomes clogged or engorged with debris,bacteria and oil,this predisposes the acne papule evolving into a pustule
Acne pustules-Relatively 2-5mm in size with visible pus-filled inflammation unlike papules.Appearance could vary from red to yellow or whitish consisting of purulent central core material.Chemical irrtation of free fatty acids in the sebum may lead to inflammation.
Acne Nodules-Nodules are deep within the skin,painful,greater than 5mm,could either be pustular or haemorrhagic.Its spread within the dermis triggers an immune response which if persistent for weeks or months hardens into a cyst or results in scarifications.
Acne Cysts-Nodular degeneration and necrosis of nodules results in abscesses that may form tracks which resemble epidermal cysts.Hair ducts,inflammatory cells,infected sebaceous gland and debris are the usuall constituents.
Progressive increase in size of inflammatory nodules which coalesce around nodules and cysts with eventual pustular eruptions results in acne conglobata.This may present as crusts,tracks,deep ulcers,ulcerated nodules and scarifications.Unrelenting pre-existing papules,pustules or cysts may serve as precursors to acne conglobata.It is a relatively severe and uncommon type of acne.They occur from comedones in groups of 2-3 which burrow forming interconnecting abscesses with eventual scars(atrophic and keloidal).They are present on the back,shoulders,face,buttocks and upper arms.The primary cause remains unknown but has been associated with exposure to halogens like dioxins,changes to propionibacterium acne reactivity and androgens.