Lymph node metastases of melanoma: Challenges for BRAF mutation detection
Journal
Human Pathology
Journal Volume
46
Journal Issue
1
Pages
113-119
Date Issued
2015
Author(s)
Abstract
Detection of B-Raf proto-oncogene, serine/threonine kinase (BRAF) mutations is required to predict response to BRAF or mitogen-activated protein kinase kinase 1 and 2 inhibitors in metastatic melanoma. Lymph node (LN) specimens carrying melanoma cells intermingled with abundant lymphocytes often contain low tumor cellularity. This study is aimed to examine challenges in the clinical detection of BRAF mutations in LN specimens with metastatic melanoma and to illustrate characteristic features of p.V600E and non-p.V600E mutations. In this retrospective study for quality assessment of the pyrosequencing assay, we compared characteristics of 53 LN and 135 non-LN formalin-fixed, paraffin-embedded specimens with metastatic melanoma submitted for BRAF mutation detection over a 40-month period. LN specimens showed a significantly higher incidence of p.V600E mutations than non-LN specimens (49% versus 22%, P <.01) but a significantly lower tumor cellularity, particularly in the case of subcapsular or infiltrative metastases. Mutant allele-specific imbalance of the p.V600E mutation was predominantly present in specimens with distant organ metastases (79% versus 27% in LN metastases versus 13% in primary cutaneous tumors or adjacent soft tissue, P <.001). p.V600K was detected in 23% of men older than 60 years old, compared with 6% in women older than 60 years old and 2% in both men and women younger than 60 years old (P <.001). LN specimens with low tumor cellularity due to numerous adjacent lymphocytes may pose a challenge to clinical detection of BRAF mutations of melanoma. The higher incidence of p.V600E mutations in LNs may prompt further studies to elucidate if the p.V600E mutation in primary tumors is associated with a higher risk of LN metastasis. ? 2014 Elsevier Inc.
Subjects
BRAF; Lymph node; Melanoma; Mutant allele-specific imbalance; Tumor cellularity
SDGs
Other Subjects
B Raf kinase; B Raf kinase; BRAF protein, human; adolescent; adult; age distribution; aged; Article; cancer incidence; cell structure; child; female; gene frequency; human; human tissue; lymph node metastasis; lymphocyte; major clinical study; male; melanoma; metastatic melanoma; middle aged; mutant; mutation; pyrosequencing; quality control; retrospective study; school child; sex difference; skin tumor; very elderly; young adult; allelic imbalance; biopsy; enzymology; genetic predisposition; genetics; lymph node; lymph node metastasis; melanoma; mutation; nucleotide sequence; pathology; phenotype; predictive value; prognosis; risk factor; secondary; Adolescent; Adult; Aged; Aged, 80 and over; Allelic Imbalance; Biopsy; Child; DNA Mutational Analysis; Female; Genetic Predisposition to Disease; Humans; Lymph Nodes; Lymphatic Metastasis; Male; Melanoma; Middle Aged; Mutation; Phenotype; Predictive Value of Tests; Prognosis; Proto-Oncogene Proteins B-raf; Retrospective Studies; Risk Factors; Skin Neoplasms; Young Adult
Publisher
W.B. Saunders
Type
journal article