Immunohistochemistry and FISH for ALK, ROS1, and RET

IHC was performed using tissue microarray slides and antibodies against anaplastic lymphoma kinase (ALK; D5F3, 1:50; Cell Signaling Technology, Danvers, MA, USA), ROS1 (D4D6, 1:50; Cell Signaling), and RET (C-19, 1:100; Santa Cruz Biotechnology, Santa Cruz, CA, USA). The IHC results were obtained using the OptiView Detection Kit (Ventana Medical System, Tucson, AZ, USA). All cases were reviewed by two experienced pathologists (YJC and HSS). All cases were further analyzed to confirm rearrangement of ALK, ROS1, and/or RET using FISH and a break-apart probe for ALK (Abbott Molecular, Abbot Park, IL, USA), a ROS1 probe (Abbott Molecular), and a RET probe (ZytoVision, Bremerhaven, Germany) [29 (link)].