Dermoscopy of Atypical Nevi Distribution of Pigmentation
Areas of homogeneous hypopigmentation and hyperpigmentation are characteristic features of atypical nevi. The distribution of hypopigmentation or hyperpigmentation varies and may be central, multifocal, or peripheral. The descriptors of pigmentation are hyperpigmentation and hypopigmentation. The distribution of the pigmentation is then classified as central hyperpigmented or hypopigmented, eccentric peripheral hyperpigmented or hypopigmented, and multifocal hyperpigmented or hypopigmented. In cases where hyperpigmentation and hypopigmentation are present, classification is based on the predominant distribution of color. The most common heterogeneous distribution of pigmentation is multifocal hyperpigmentation or hypopigmentation, followed by central hypopigmentation and central hyperpigmentation. Eccentric peripheral hyperpigmentation is the least common form. Eccentric peripheral hyperpigmentation is also often found in malignant melanoma.
All of this sounds very confusing. Just remember that atypical nevi can have two different structural components and homogenous pigmentation can have a variety of patterns. All structures and pigmentation must be uniform to make a diagnosis of a benign lesion.