Upward epidermal migration of single melanocytes

Usually confined to lower half of epidermis

Focal confluent melanocytic proliferation

Most frequent in first year of life

Atypical melanocytic proliferation in a congenital melanocytic nevus

Cohesive cellular nodules of melanocytes within dermal component

Epithelioid, spindle or small cell morphology

Cells are uniform, lack overt atypia

Blend with surrounding dermal component, which shows maturation

Atypical dermal melanocytic proliferation in a congenital melanocytic nevus