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Post-inflammatory hyperpigmentation


Ms. Cheung sought medical attention for a patch of dark brown pigmentation on her face. She had developed the hyperpigmentation six months ago after improperly treating an inflamed skin injury that left a scar. She tried several over-the-counter skin lightening products without success. Upon diagnosis, it was confirmed to be deep pigmentation. What causes pigmentation and how can it be treated?

Post-inflammatory hyperpigmentation (PIH) is mainly caused by skin inflammation, such as infections, allergies, and injuries. Inflammation triggers melanocytes to produce more melanin, and keratinocytes release melanin, which is then transferred to the dermis by macrophages. Pigmentation can be classified into epidermal or dermal pigmentation, with the former being easier to treat and typically appearing as gray-blue. The severity of pigmentation depends on the degree of inflammation, injury, and skin type, with those with darker skin being more prone to it. If left untreated, pigmentation can persist for several months to years or even be permanent.

Like Ms. Zhang, patients often opt for over-the-counter skin lightening products instead of seeking medical treatment. However, the earlier pigmentation is treated, the better the outcome. Before treating pigmentation, the underlying skin issue must be addressed. Proper sun protection is also crucial in preventing exacerbation of pigmentation. Treatment options include medication, chemical peels, and laser therapy. Medications such as hydroquinone, azelaic acid, kojic acid, retinoids, and vitamin C can help lighten pigmentation. Chemical peels involving alpha-hydroxy acids, salicylic acid, and trichloroacetic acid can also be effective. Laser therapy involving 510nm, 532nm, 694nm, 755nm, and 1064nm wavelengths can absorb melanin to reduce pigmentation but carries risks of hyperpigmentation. A combination of treatment options may be recommended based on the patient’s condition.

Regardless of the treatment, patience is necessary in addressing pigmentation. Patients should avoid using over-the-counter skin lightening products and seek medical attention promptly.