Association of the BRAFV600E Mutation With Morphology and Heterogeneity in Melanoma

Abstract

The BRAFV600E mutation test for melanoma patients has become the key to precision therapy. In this study, we compared the concordance of immunohistochemistry (IHC), quantitative real-time PCR (qPCR), and next-generation sequencing (NGS) in detecting the BRAFV600E mutation in a Chinese melanoma patient population. In addition, this study evaluated the BRAFV600E mutation heterogeneity between primary and metastatic melanoma sites, as well as within the same lesion, and investigated the association between BRAFV600E mutation status and tumor cell morphology. A total of 880 samples from 555 patients diagnosed with malignant melanoma were collected, and IHC for BRAFV600E was conducted. Of these, 385 were subjected to qPCR and 115 to NGS concurrently. Inter and intratumor heterogeneities of BRAFV600E mutations were compared. Hematoxylin and eosin (H&E) stain was performed, and the cell morphologies were reviewed. The IHC and qPCR results were discordant in 14 cases, yielding a concordance rate of 96.36%. IHC and NGS results showed a concordance rate of 97.39%. The sensitivity and specificity of BRAFV600E detection by IHC were 96.95% and 99.46%, with an overall concordance rate of 98.80%. One of 130 patients (0.77%) showed intertumor heterogeneity, and 3 of 880 samples (0.34%) showed intratumor heterogeneity. VE1 staining patterns significantly differed across cell morphologies (P < .01). Compared with qPCR and NGS, VE1 IHC offers high sensitivity, specificity, and consistency in detecting the BRAFV600E mutation in melanomas. The BRAFV600E mutation in melanoma exhibits low intertumor and intratumor heterogeneities and is significantly associated with tumor cell morphology; tumors with epithelioid cell morphology are most likely to harbor the BRAFV600E mutation.