Dermatology Case Studies

Nevi (singular nevus), more commonly known as moles, are observed in most healthy skin and are more common in those with white skin

They are highly coloured (from light brown to black) small collections of highly pigmented melanocytes within the dermis

They can be present at birth or can newly appear in the skin of younger people
Please click the buttons below to learn about each type of nevi:

Figure 4. Examples of Melanocytic nevi

Melanocytic nevi

Melanocytic nevi are collections of highly pigmented melanocytes within the dermis
These types of moles vary in colour in different skin tones (usually brown-black) and are easier to see on pale skin
Some moles are present at birth or appear within the first two years of life and these are known as congenital melanocytic nevi
Moles can continue to appear in the skin of people up to around 30-40 years of age (acquired melanocytic nevi)
Thereafter, all new moles need to be checked and monitored
Melanocytic nevi can be found on any part of the body and can be flat or elevated
They can vary in colour from fleshy/pink to dark brown, blue or black
They are predominantly round or oval in shape but they can also be irregular
They are usually small (less than 5mm in diameter) but can reach a few centimetres in diameter

Figure 5. Examples of Dysplastic nevi

Dysplastic nevi

Dysplastic (or atypical) nevi are benign moles but with the capacity to transform to the dangerous skin cancer cutaneous melanoma
They have some different features but can be hard to distinguish from simple nevi
They are usually longer than 5mm in diameter
They usually appear as flat, slightly raised plaques, with a pebbly/ slightly scaly surface
They can also appear as target-like lesions with a darker raised centre and irregular borders
A dysplastic nevus can range in colour from pink to dark brown
Dysplastic nevi can be found in almost any area of the body
Its important to note that not all dysplastic nevi will transform to melanoma
It can also be hard to distinguish dysplastic and simple nevi on routine inspection
It is essential for patients to know that any pigmented lesion, anywhere on the skin which is changing should be brought to medical attention
Some changes for which people with any pigmented nevi should seek medical advice include: