Introduction Hyperpigmentation is one of the most common conditions encountered in dermatological and aesthetic practice. It results from a disturbance in the production or distribution of melanin within the skin. This condition represents a clinical challenge due to its multiple causes, varying depths, and different responses to treatment. Pathophysiology Melanin is produced within melanocytes located in the basal layer of the epidermis through a series of enzymatic reactions involving the enzyme tyrosinase. Melanin is then transferred to keratinocytes, where it plays a key role in protecting the skin from ultraviolet radiation. Any disruption in this process can lead to hyperpigmentation, which may occur through: • Increased activity of melanocytes • Increased number of melanocytes • Increased transfer of melanin • Deposition of melanin in the dermis Triggering Factors • Ultraviolet (UV) radiation • Skin inflammation • Hormonal factors • Medications • Genetic factors Clinical Classification • Epidermal pigmentation → responds well to treatment • Dermal pigmentation → difficult to treat • Mixed type Clinical Application Wood’s lamp is used to determine the depth of pigmentation, which helps in selecting the appropriate treatment, such as: • Topical creams • Chemical peels • Laser therapy Conclusion Hyperpigmentation is a multifactorial condition, and understanding its pathophysiology is essential for selecting the appropriate treatment and avoiding complications. Prepared by: Dr. Hussein Safaa Abdul Amir Al-Mustaqbal University – The First University in Iraq