Melanocytes are found distributed in the skin

• Scattered as individual cells at the junction of the upper (epidermis) and lower (dermis) layers of the skin. These cells produce granules of pigment (a suntan) in response to ultraviolet exposure.
  
  
• Aggregated together (termed naevus cells) at various depths within the epidermis and dermis. Characteristic patterns of aggregation can usually be recognized by expert clinicians as those forming junctional, dermal, compound and dysplastic naevi (moles).

A number of changes in the pigment cell (melanocyte) network of the skin can be identified as potentially cancerous.

The Dermascope is an instrument which allows groups of pigment cells within the skin to be examined for changes which signal the development of a melanoma. It is a microscope which is used on living skin. Properly used, this instrument can substantially reduce the need to excise many naevi. Dermoscopy has greatly aided the diagnostic process.