Patterns of distribution of giant congenital melanocytic nevi (GCMN): The 6B rule.
BACKGROUND
Garment-related terms have been used to describe the pattern of distribution of giant congenital melanocytic nevi (GCMN).


OBJECTIVE
We sought to describe patterns of distribution of GCMN and propose a classification scheme.


METHODS
Photographic records of patients with GCMN from the Hospital Clinic of Barcelona were analyzed and a classification based on observed GCMN distribution patterns was created. The classification was independently applied by 8 observers to cases found in the literature. The interobserver agreement was assessed.


RESULTS
Among 22 patients we observed 6 repeatable patterns of distribution of GCMN, which we termed the "6B": bolero (involving the upper aspect of the back, including the neck), back (on the back, without involvement of the buttocks or shoulders), bathing trunk (involving the genital region and buttocks), breast/belly (isolated to the chest or abdomen without involvement of bolero or bathing trunk distributions), body extremity (isolated to extremity), and body (both bolero and bathing trunk involvement). Our literature search found 113 cases of GCMN, which we were able to classify into 1 of the 6B patterns with an overall kappa of 0.89.


CONCLUSIONS
Some patterns occur infrequently with a dearth of images available for analysis.


CONCLUSIONS
The anatomic distribution of GCMN occurs in 6 recognizable and repeatable patterns.
Melanoma Unit, Department of Dermatology, Hospital Clinic of Barcelona, University of Barcelona, Barcelona, Spain.
Vanessa P
VP
Martins da Silva
Department of Dermatology, Memorial Sloan Kettering Cancer Center, New York, New York.
Ashfaq
A
Marghoob
Melanoma Unit, Department of Dermatology, Hospital Clinic of Barcelona, University of Barcelona, Barcelona, Spain.
Ramon
R
Pigem
Melanoma Unit, Department of Dermatology, Hospital Clinic of Barcelona, University of Barcelona, Barcelona, Spain; "Centro de Investigación Biomédica en Red en Enfermedades Raras, Instituto de Salud Carlos III", Barcelona, Spain.
Cristina
C
Carrera
Melanoma Unit, Department of Dermatology, Hospital Clinic of Barcelona, University of Barcelona, Barcelona, Spain.
Paula
P
Aguilera
"Centro de Investigación Biomédica en Red en Enfermedades Raras, Instituto de Salud Carlos III", Barcelona, Spain; Department of Biochemical and Molecular Genetics, Hospital Clínic, IDIBAPS, University of Barcelona, Barcelona, Spain.
Joan A
JA
Puig-Butillé
Melanoma Unit, Department of Dermatology, Hospital Clinic of Barcelona, University of Barcelona, Barcelona, Spain; "Centro de Investigación Biomédica en Red en Enfermedades Raras, Instituto de Salud Carlos III", Barcelona, Spain.
Susana
S
Puig
Melanoma Unit, Department of Dermatology, Hospital Clinic of Barcelona, University of Barcelona, Barcelona, Spain; "Centro de Investigación Biomédica en Red en Enfermedades Raras, Instituto de Salud Carlos III", Barcelona, Spain. Electronic address: jmalvehy@gmail.com.
Josep
J
Malvehy
D005260:Female; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D008545:Melanoma / Q000453:epidemiology; D009508:Nevus, Pigmented / Q000145:classification* / Q000151:congenital / Q000473:pathology; D015588:Observer Variation; D009928:Organ Specificity; D010781:Photography; D015203:Reproducibility of Results; D012306:Risk; D012878:Skin Neoplasms / Q000145:classification* / Q000151:congenital / Q000473:pathology
benign skin tumors; classification; congenital melanocytic nevus; distribution; giant nevus; skin neoplasms