title: BRAF-V600 Mutation Heterogeneity in Primary and Metastatic Melanoma: A Study With Pyrosequencing and Immunohistochemistry.
abstract: BACKGROUND
  The BRAF-V600 mutation is the most common mutation in cutaneous melanomas and is currently considered a target mutation when planning treatment for metastatic melanoma patients. Various techniques are used to determine the mutation status. The aim of this study was to determine the BRAF-V600 mutation status in primary and metastatic foci of melanoma cases and the consistency between the results of immunohistochemical and molecular methods.
  
  
  METHODS
  A total of 48 primary or metastatic cases were included in the study. Pyrosequencing was used as the molecular method and the VE1 antibody for immunohistochemical evaluation when determining the BRAF-V600 mutation.
  
  
  RESULTS
  The BRAF-V600 mutation was found in 75 of the 96 tumors (78.1%) from the 48 cases. V600E and V600K were present in 60 and 10 tumors, respectively, whereas V600R and V600M were present in 2 tumors and V600G in 1 tumor. There was no mutation in 5 metastases (12.8%) of the 39 cases with a V600 mutation in the primary tumor and no mutation in the primary tumor of 2 of the 36 cases (5.6%) with the V600 mutation in the metastasis. Fifty-six tumors were immunohistochemically positive where a V600E mutation was detected with pyrosequencing. Wild-type tumors (n = 20) and tumors with non-V600E mutations (n = 15) on pyrosequencing were immunonegative with VE1. The sensitivity and specificity of immunohistochemistry were 93.3% and 97.2%, respectively.
  
  
  CONCLUSIONS
  In conclusion, BRAF-V600 mutation inconsistencies of up to 14.5% can be seen between the primary and metastatic foci in melanoma cases. These findings should be taken into account when planning targeted therapy and deciding on treatment responsiveness/unresponsiveness. An immunohistochemical method can be used as the first step to detect a BRAF-V600 mutation but additional molecular methods should be used when immunohistochemistry results are negative.
authors.affiliation: Department of Pathology, Faculty of Medicine, Ege University, Izmir, Turkey.
authors.forename: Banu
authors.initials: B
authors.lastname: Yaman
authors.forename: Gülşen
authors.initials: G
authors.lastname: Kandiloğlu
authors.forename: Taner
authors.initials: T
authors.lastname: Akalin
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000235:genetics*; D004252:DNA Mutational Analysis / Q000379:methods*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008545:Melanoma / Q000201:enzymology / Q000235:genetics* / Q000556:secondary* / Q000628:therapy; D008875:Middle Aged; D011237:Predictive Value of Tests; D011379:Prognosis; D048493:Proto-Oncogene Proteins B-raf / Q000235:genetics*; D015203:Reproducibility of Results; D012878:Skin Neoplasms / Q000201:enzymology / Q000235:genetics* / Q000473:pathology* / Q000628:therapy
chemical_list: D014408:Biomarkers, Tumor; C482119:BRAF protein, human; D048493:Proto-Oncogene Proteins B-raf