A mole is a melanocytic naevus, Latin for ‘birthmark’, a nest of pigment cells or melanocytes embedded in the skin. Naevi are well circumscribed lesions and can vary from flat to raised or nodular. They are designated according to their depth within the skin and can be intradermal or embedded deep within the skin or raised to varying heights and known as compound naevi. They can appear similar and may be confused with the malignant melanoma but naevi have not malignant potential for uncontrolled growth or metastasis.

Naevi can also be confused with freckles known as ephilis which are pigmented skin lesions with a normal number of melanocytes with an increased amount of melanin pigment. Naevi can also be confused with lentigo or lentigines which are dark brown skin lesions with an increased number of pigment cells or melanocytes. More seriously a form a melanoma occurring especially on palms, under nails and on the soles of the feet known as acral letiginous melanoma can appear similar to a benign lentigo in some circumstances.

A dysplastic naevus is an atypical melanocytic naevus or simple mole that is larger than a normal mole with irregular borders and variegated non-uniform pigmentation. Simply put a dyplastic naevus is a mole that doesn’t appear quite right and should be treated as suspicious and considered for biopsy or excision. A single dysplastic naevus can usually be easily excised but some individuals may have dozens of dysplastic naevi distributed over their bodies requiring lifelong surveillance as each dysplastic naevus or dysplastic mole can change and develop malignant potential and is a precursor to a melanoma.

Dysplastic naevus syndrome is an inherited familial disorder where affected individuals from affected families may have hundreds of atypical naevi all of which have lifelong malignant potential and require close surveillance. Whole body digital photography of course is invaluable in periodic assessment for change in lesions. In affected individuals it is impossible to remove all naevi but many excisional biopsies are performed for removal of suspicious lesions.