New Categories Proposed To Classify Congenital Melanocytic Nevi

Categories: CMN Research

By Patricia McAdams, Staff Writer, Nevus Outreach

Sven Krengel

Sven Krengel

In a paper accepted for publication in an upcoming issue of the Journal of the American Academy of Dermatology, Sven Krengel, MD, Ash Marghoob, MD, and their colleagues in Europe, Israel, and the United States, propose a new consensus classification for congenital melanocytic nevi (CMN). Krengel, Department of Dermatology, Medical University, Lübeck, Germany, says that this new classification tool will help interdisciplinary scientists and patient organizations in establishing an international platform for CMN research, thus furthering international collaborations.

Krengel described the proposed categories to participants at the 2012 Nevus Outreach Conference held in Texas earlier this month. This classification is intended to describe the preponderant, or greatest, area of involvement of CMN by projected adult size, location, and other characteristics. Categories will be shown by code as follows:


CMN Projected Adult Size
Acronym Code Centimeters Inches
Small CMN (SCMN) “SCMN” Less than 1.5 cm Less than an inch
Medium CMN (MCMN) “M1” 1.5 to 10 cm About 1 to 4 inches
“M2” 10 to 20 cm 4 to 8 inches
Large CMN (LCMN) “L1” 20 to 30 cm 8 to 12 inches
“L2” 30 to 40 cm 12 to 16 inches
Giant CMN (GCMN) “G1” 40 to 60 cm 16 to 24 inches
“G2” Greater than 60 cm Greater than 24 inches
Multiple MCMN “mMCMN” Three or more MCMN without a single predominant CMN.
CMN Localization. One or more of these localizations should be used to describe the largest area of CMN involvement.
CMN of the head “face,” “scalp”
CMN of the trunk “neck,” “shoulder,” “upper back,” “middle back,” “lower back,” “breast/chest,” “abdomen,” “flank” or side, “gluteal region” or buttocks, “genital region”
CMN of the extremities “upper arm,” “forearm,” “hand,” “thigh” “lower leg,” “foot”
CMN Description
“C0,” “C1,” or “C2” None, moderate, or marked color heterogeneity or differences
“RO,” “R1,” or “R2” None, moderate, or marked surface wrinkles or ridges
“NO,” “N1,” or “N2” None, scattered, or extensive nodules, or swelling, in the dermal or subcutaneous (connective tissue) layers of skin
“H0,” “H1,” or “H2” None, notable, marked hairiness

Satellite Nevi

In addition to describing larger CMN in detail, the number of satellites within the first year of life will be counted. In those instances when that number is unavailable, the current actual number should be shown.

Satellite codes are as follows:

Code Number of satellites
“S0” No satellites
“S1” Fewer than 20 satellites
“S2” 20 to 50 satellites
“S3” More than 50 satellites

A given patient’s nevi might thus be identified with a series of codes to describe the nevi at any point in time. For example: “G1,” lower back, “S1,” “C2,” “R1,” “N2.”

Progress has been made in the diagnostic and therapeutic management of CMN and the risk of malignant transformation, but much work remains to be done. The description of CMN with the consistent terminology proposed above will facilitate collaborative studies among both clinicians and researchers around the world.

“This classification will help to link possible risks — most importantly cutaneous melanoma, neurocutaneous melanocytosis, and central nervous system melanoma — to certain subtypes of CMN,” says Krengel. “As yet, it is largely unknown if certain morphological variants of CMN are at higher risk than others.”

After explaining the new CMN categories to Conference participants, Krengel invited those with nevi to have them categorized as shown above in an effort to validate the usefulness of this new tool for basic and clinical research. Harper Price, MD; Judy O’Haver, PhD; and Kellie Badger, RN, from Phoenix Children’s Hospital, Phoenix, Ariz., actually set up this study. Price and Marghoob are the principal investigators. Forty-three individuals with CMN participated in this research.

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