Many of us have birthmarks that make us unique and beautiful. These pigmented birthmarks, or “congenital melanocytic nevi”, can come in many different shapes and sizes. It is important to distinguish and understand these beauty marks, however, they could mean different things when it comes to your skin and the overall health.
Birthmarks: Congenital melanocytic nevi (CMN) are classified as benign tumors – in other words, they are not cancerous in the beginning. They represent an overgrowth of melanocytes, the cells that produce pigment in your body.These marks or nevi appear at birth or within the first few months of our life. They can be found in people of any skin type or background. CMN are believed to arise from the abnormal migration and development of melanocytes during fetal development. These lesions can be of various shapes, sizes, and locations. The CMN condition is usually defined by the size of the largest nevus on your body, with the following groupings :
- Small: < 1.5cm
- Medium: 1.5-19.9 cm
- Giant: >= 20cm
These marks can have hair follicles that grow within them, may feel different than the rest of the skin to the touch, and often grow proportionally with the child/person. People with CMN may have no other associated symptoms, or may have many other “satellite” moles and birthmarks across the rest of their skin. CMN lesions may also be a part of a neurocutaneous melanocytosis: a condition with excess pigment cells in the brain or spinal cord, that can lead to additional neurological symptoms.
In general, small and medium CMN are relatively benign, and the risk of these lesions becoming cancerous as compared to the rest of your skin is very low. That said, they should be monitored for any changes and growth, and you should use a good quality sunscreen with SPF 30 or higher for all your skin. It is also important to do regular skin self-examinations to observe any changes in your moles/nevi. You can take photos of your moles once a year with a ruler being in the picture on your skin (as shown) to keep a good eye on them, and you should consult a certified dermatologist if there are any worries or abnormal changes. For patients with giant CMN, early surgical removal is ideal for not only aesthetic reasons but more importantly the fact that the risk of these lesions becoming cancerous is notably higher, especially during the first five years of life. Giant CMN lesions near/on the back or the trunk, and the presence of multiple satellite nevi, are associated with the greatest risk of developing a melanoma. At times in giant melanocytic nevi a small part of it may start to grow, change or bleed – if this happens, please show this spot to a certified dermatologist.
A summary of the recommended management is represented in the diagram below:
