The T1796A mutation of the BRAF gene is absent in Spitz nevi.
BACKGROUND
BRAF, a serine/threonine kinase, is a component of the retrovirus-associated sequence (RAS)-RAF-extracellular-regulated protein kinase (ERK)-MAP kinase signal transduction pathway mediating signals from RAS to ERK. The T1796A single point mutation in exon 15 of the BRAF gene has recently been reported in a high percentage of malignant melanomas and benign melanocytic lesions such as congenital nevi, compound nevi, intradermal nevi and dysplastic nevi. The T1796A mutation has been shown to promote cell proliferation.


METHODS
We screened 21 Spitz nevi and six spitzoid malignant melanomas for the presence of the T1796A BRAF mutation.


RESULTS
The T1796A BRAF mutation could not be detected in any of the 21 Spitz nevi but was present in two of the six spitzoid malignant melanomas.


CONCLUSIONS
Our results, in conjunction with data from a previous investigation, suggest that the melanocytic proliferation of Spitz nevi might be induced by components of the RAS-RAF-ERK-MAP kinase pathway different from BRAF, possibly combined with other genetic aberrations. The lack of the T1796A BRAF mutation might be of practical importance in distinguishing Spitz nevi from other melanocytic lesions simulating Spitz nevi as a part of a future complex diagnostic assay.
Dermatopathologische Gemeinschaftspraxis, Friedrichshafen, Germany. palmedo@dermpath.de
Gabriele
G
Palmedo
Markus
M
Hantschke
Arno
A
Rütten
Thomas
T
Mentzel
Heino
H
Hügel
Michael J
MJ
Flaig
Amir S
AS
Yazdi
Christian A
CA
Sander
Heinz
H
Kutzner
D001483:Base Sequence; D004252:DNA Mutational Analysis; D003937:Diagnosis, Differential; D006801:Humans; D008545:Melanoma / Q000235:genetics*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D018332:Nevus, Epithelioid and Spindle Cell / Q000235:genetics*; D017354:Point Mutation; D016133:Polymerase Chain Reaction; D048493:Proto-Oncogene Proteins B-raf; D019908:Proto-Oncogene Proteins c-raf / Q000235:genetics* / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D012878:Skin Neoplasms / Q000235:genetics*; D018631:ras Proteins / Q000378:metabolism
C482119:BRAF protein, human; D048493:Proto-Oncogene Proteins B-raf; D019908:Proto-Oncogene Proteins c-raf; D020928:Mitogen-Activated Protein Kinases; D018631:ras Proteins