- Extremely common, especially in individuals with more darkly pigmented skin
- Develops after inflammation or injury to the skin, but preceding inflammation may be transient or subclinical
- The increased melanin can be primarily within the dermis (eg. following lichen planus) or in the epidermis (ex. following acne or atopic dermatitis)
- Epidermal hyperpigmentation fades more readily than dermal hyperpigmentation