Global CMN Awareness Day Date in the current year: September 28, 2026

“Nevus” is an umbrella term that can describe several types of benign, chronic skin or mucosal lesions. In the case of a “congenital melanocytic nevus”, “congenital” means that the nevus is present at birth but is not necessarily hereditary, whereas “melanocytic” indicates that the nevus is caused by an uneven distribution of pigment-producing cells called melanocytes.

Congenital melanocytic nevi can range in size from less than 2 cm to covering a large portion of the body. Small nevi, which are less than 1.5 cm in diameter, are relatively common, affecting about 1% of infants. Medium, large, and giant nevi, however, are increasingly rare.

There is some disagreement over what constitutes a large nevus. Some clinicians classify nevi measuring between 20 and 40 cm as large. Others use the palm of the patient’s hand or body surface area as a reference (a nevus larger than the palm or covering more than 2% of the body is considered large). Nevi that cover a large portion of the head, legs, or arms may be considered large, even if they do not meet the previous criteria. Giant nevi cover a large area of the body, typically the torso, and often have prominent terminal hair. They are usually accompanied by smaller nevi.

While congenital melanocytic nevi are generally benign, large and giant nevi carry an increased risk of melanoma. It is estimated that at least 2% of individuals with large congenital melanocytic nevi will develop melanoma. Currently, however, it is impossible to predict whether a person with a large or giant nevus will develop melanoma.

The standard treatment for congenital melanocytic nevi is surgical removal, if chosen. Small nevi are typically removed for psychological and aesthetic reasons, while larger ones may be excised to reduce the risk of cancer. However, removing a large nevus is not a simple procedure because it usually requires multiple surgeries and skin grafts to replace the removed tissue.

There is no universal recommendation for surgical removal, so the decision to undergo surgery is made on a case-by-case basis after weighing all pros and cons. Patients with large nevi who do not undergo surgical excision may require day-to-day management, such as hair removal and creams or lotions to alleviate itching, which can be problematic. It is important to approach hair removal with care because nevus skin may be more fragile than regular skin. Regular monitoring is also highly advisable.

Global CMN Awareness Day was launched by the US-based nonprofit organization Nevus Outreach, which is working to raise awareness, foster a supportive community, and advance research for people affected by CMN and related conditions. The main goals of this day are to educate the public about the condition, combat the surrounding stigma, provide support to those affected, and promote early diagnosis and further research.