Concomitant BRAF V600E and NRAS Q61R mutations in the same thyroid nodule: a case report.

Background: Papillary thyroid cancer (PTC) is the most common type of well-differentiated endocrine malignancy. Generally, thyroid nodules with multiple oncogenic mutations are uncommon with an occurrence which may be related to more aggressive biological behavior of tumors. RET/PTC rearrangement, RAS, and BRAF mutations are considered to be mutually exclusive in PTC. Concomitant RET/PTC, RAS, or BRAF mutations have been documented, although the impact of these mutations for tumor growth and survival is debated.

Case description: Here we present a rare case of woman 46 years old with a neck mass and thyroid nodule classified as TIR5 on cytological examination. We found contemporary BRAF p.(Val600Glu) [p.(V600E); c.1799T>A] and NRAS p.(Gln61Arg) [p.(Q61R); c.182A>G] mutations in morphologically different areas within the same lobe (the right one); The two lesions show different morphology. The mutated BRAF lesion showed morphological characteristics compatible with classic papillary carcinoma. The mutant NRAS lesion shows morphological features compatible with follicular variant papillary carcinoma. To the best of our knowledges, this is the first time that such mutations, which are normally mutually exclusive, have been detected at the same time.

Conclusions: The finding of synchronous mutations is a rare occurrence suggesting for intratumoral heterogeneity (ITH) even in PTC. Patients with multiple mutations have a clinical worse prognosis, generally characterized by an aggressive thyroid cancer, which may influence the surgical treatment, chemotherapy, and BRAF V600E mutation-targeting therapy.