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Handling Post-inflammatory Hyperpigmentation
By: Christine Heathman
Posted: September 28, 2012, from the October 2012 issue of Skin Inc. magazine.
page 2 of 4
Racial and ethnic differences in skin color are due to the number, size and aggregation of melanosomes within the melanocyte and keratinocytes. Racial or ethnic differences in the size and aggregation of melanosomes within keratinocytes have been clearly established. In Caucasian global skin types, melanosomes are smaller in size than those in black skin and contain less melanin.
It has also been determined that melanosomes are larger, more oval and denser in dark-skinned individuals compared to lighter-skinned individuals. Similarly, not all white and Asian skin has small melanosomes, nor are the melanosomes always aggregated. Total melanin content is greater in people with darker skin compared to those with lighter skin.
The amount of melanin is the very basis of skin-typing classification, an important factor in cataloging skin history for UV radiation reaction. The increase of epidermal melanin content of darker-skinned individuals provides greater intrinsic photo protection. Simply put, higher melanin concentration translates into better photo protection from UV radiation and delays the clinical appearance of photoaging brought on by photodamage, especially in lighter skin types that are more prone to UV burn.
Melanosome groupings are also affected by sun exposure. Asian skin exposed to sunlight has a predominance of nonaggregated melanosomes, whereas unexposed skin has predominately consolidated melanosomes. The effects of UV and visible light on human skin include sunburn, suntan, phototoxic and photoallergic reactions, as well as post-inflammatory hyperpigmentation (PIH).
Post-inflammatory hyperpigmentation (PIH)
One of the most common pigmentation disorders of clients with darker skin is PIH, which is one type of pigmentation morbidity. PIH can be considered the default pathophysiologic response to cutaneous injury of darker global skin of colors. This response is the belief predicated on the labile response of melanocytes to irritation or inflammation. The common link to any pigmentation disorder is inflammation. Darker skin differs from Caucasian skin in its reactivity and clinical presentation. Although ongoing research continues to unveil aggravating factors, significant prudence in understanding this problem still remains to be practiced in the area of ethnic skin disorders to properly manage them.