PMC7085839_01
(a) An H&E-stained tissue section of the thyroid tumor at 100x (left) and 200x (right) magnification is shown. The tissue shows solid sheets and nests of cells separated by hyalinized fibrovascular stroma. Interspersed between the cells is a homogeneous, acellular, eosinophilic, extracellular matrix material, consistent with amyloid (solid yellow arrow). There are numerous scattered calcifications (solid blue arrow). Cytologically, the tumor cells are spindled, plasmacytoid, or polyhedral in shape with round to oval nuclei showing stippled, fine, uniform salt and pepper nuclear chromatin, and a moderate amount of pink granular cytoplasm. These findings are consistent with the diagnosis of medullary thyroid carcinoma. (b) Integrated Genomics Viewer representative display of the mutated sequence in BRAF detected by the next-generation sequencing analysis. Separate sequencing reads at this nucleotide position (1799) are shown. A (green) to T (red) nucleotide substitution (variant allele frequency, 10.3%) results in an amino acid substitution (glutamic acid for valine) at codon 600 of BRAF. (c) Presence of the BRAF p.V600E mutation was confirmed by multiplexed PCR and single-base extension with mass spectrometry analysis on the Sequenom instrument (Agena Biosciences). The mass (x-axis) and intensity (y-axis) of the BRAF peaks are shown. The blue arrow indicates the wildtype BRAF peak, and the red arrow indicates the mutant BRAF peak. The T to A nucleotide substitution shows results in an amino acid substitution (glutamic acid for valine) at codon 600 of BRAF.
CRIE2020-7641940.001.jpg
PMC7085839_01_CRIE2020-7641940.001.jpg
fig1
Pathological analysis after a total thyroidectomy and central neck lymph node dissection revealed a 1.8 cm MTC (Figure 1(a)) with multifocality, extrathyroidal extension, and MTC in 6 out of 10 lymph nodes. The only abnormality detected was a BRAF p.V600E mutation (Figure 1(b)). The presence of a BRAF p.V600E mutation was then confirmed by an alternate testing platform (Figure 1(c)).