NTRK1/3, ALK, and ROS1 translocations have been reported in a minor subset of papillary thyroid carcinomas (PTCs). We aimed to elucidate the prevalence and clinicopathological characteristics of these gene rearrangements and the utility of immunohistochemistry (IHC) in PTC and anaplastic thyroid carcinoma (ATC). We screened nonradiation-exposed cases of 307 PTCs and 16 ATCs by IHC for pan-Trk, ALK, and ROS1, followed by fluorescence in situ hybridization (FISH). In the PTC group, IHC for pan-Trk, ALK, and ROS1 was positive in 18 cases (5.9%), 1 case (0.3%), and 12 cases (3.9%), respectively. Among the pan-Trk IHC–positive cases (n = 18), 2 cases (11.1%; 0.7% of all PTCs) had NTRK1 or NTRK3 gene rearrangement with conventional PTC histology. The ALK IHC–positive case (n = 1) was the follicular variant of PTC with consistent ALK gene rearrangement. ROS1 gene rearrangement was not detectable in the ROS1 IHC–positive PTCs (0/12) by FISH. Most (approximately 70%) of the pan-Trk or ROS1 IHC–..... READ ARTICLE
Human Pathology DOI:10.1016/j.humpath.2020.09.004
Authors: Yui Nozaki, Hidetaka Yamamoto, Takeshi Iwasaki, Masanobu Sato, Rina Jiromaru, Takahiro Hongo, Ryuji Yasumatsu, Yoshinao Oda