Birthmarks and NaeviDr Daniel HewittDermatologistSkin and Cancer Foundation Westmead
ObjectivesTo understand that there are many different types of birthmarks and naevi.To appreciate the main clinical characteristics of the most common types.
Paediatric dermatologyMany skin conditions affect children.Atopic dermatitis and viral exanthems have been discussed. Most inflammatory dermatoses can affect both adults and children.Here we will only discuss the more common naevi and birthmarks.
Naevi and birthmarksA naevus is literally a “maternal impression.”They can be interpreted as aberrations of embryological development comprising a proliferation of one or more cell types.Any of the cell types in the skin can produce a naevus.
The most common naevi are melanocytic naevi vascular naevi and sebaceous naevi
Melanocytic naeviThese are usually brown, often hairy lesions of variable size.They usually need no specific management.They can be excised for cosmetic reasons.Acquired melanocytic naevi are related to sun exposure and increase in number in the late teens and early twenties. These are the common "moles" all fair skinned people living in Australia develop.Congenital melanocytic naevi are present at birth.They are categorized according to size Small up to 1.5cm maximum diameter Medium 1.5cm to 20cm maximum diameter Giant greater than 20cm maximum diameter
There are other pigmented birthmarks.The most common is the Mongolian Spot. These are very common in pigmented races. They represent dermal melanocytosis, have no medical implications and fade by 5-7 years.
Vascular birthmarksThere are two main types – infantile haemangiomas and vascular malformations.It is very important to understand the difference in these as the natural histories and managements are completely different.
Infantile haemangiomasThese are benign tumours of vascular endothelium, characterized by a proliferative and an involutional phase.Most often they can be observed with no specific management as they involute.Infantile haemangiomas can be superficial (“strawberry birthmark,”) mixed or deep (“cavernous.”)
Generally haemangiomas proliferate over 6-10 months and involute over 5-7 years.However, complications of haemangiomas include Ulceration Ocular compromise Airway compromise High output cardiac failure Disseminated intravascular coagulation Systemic involvement ScarringSuch occurences may necessitate treatment with vascular laser, topical steroids, systemic steroids or systemic propranolol
Vascular malformationsThese are a developmental anomaly, predominantly capillary in origin, but sometimes derived from venous, arterial or lymphatic vessels. They are present at birth and persist throughout life.Vascular laser is often used to treat these early as they generally get thicker and more prominent over time.They are commonly known as “port wine stains.”
Capillary vascular malformationsand the thickening that maydevelop in adult life
Capillary vascular malformations can be associated with other abnormalities.The most well known syndrome isSturge-Weber Syndrome. This is a facial vascular malformation involving at least a portion of V1 in association with leptomeningeal angiomatosis and often glaucoma.
Sebaceous naeviThese are birthmarks of sebaceous glands.They are slightly raised, linear or oval in shape andyellow or orange in colour.They are most common on the scalp and oftendevoid of hair.They have a 15% chance of developing amalignancy so are frequently excised.Rarely, and if very large they can be associatedwith abnormalities of bony growth, the eyesand the central nervous system.
ConclusionThere are many different types of birthmarks and naevi.This is a very brief introduction to the most common.These lesions are usually harmless, but occasionallythere can be serious complications which require specificmanagement.