Mammaglobin clone 304 1a5

IHC stains were performed using 4-μm-thick formalin-fixed paraffin-embedded (FFPE) sections of selected representative tissue blocks from the 11 NTRK-rearranged thyroid tumors. A Bond 3 automated stainer (Leica Microsystems, Bannockburn, IL) and compatible primary antibodies for S100 protein (polyclonal and prediluted; Ventana, Oro Valley, AZ), mammaglobin (clone 304-1A5; dilution 1:250; Dako, Carpinteria, CA), GATA3 (clone L50-823, dilution 1:200; Cell Marque, Rocklin, CA), PAX8(polyclonal, dilution 1:1000; Proteintech, Rosemont, IL), TTF1 (clone 8G7G3/1; dilution 1:300; Dako, Carpinteria, CA), BRAF V600E (clone VE1; dilution 1:200; Abcam, Cambridge, United Kingdom), thyroglobulin (dilution 1:800; Cell Marque, Rocklin, CA) and HBME1 (prediluted; Ventana, Oro Valley, AZ) were used. Appropriate positive and negative controls were included. Stained slides were reviewed by three pathologists (VN, PMS, and YHC) and graded as negative (0% tumor cells stained), focal (<50%) and diffuse (>50%).

Immunohistochemical studies were performed using 4- to 5-μm-thick, formalin-fixed paraffin-embedded (FFPE) sections of selected blocks for 11 patients diagnosed with RET-rearranged salivary gland carcinomas in a Bond 3 automated immunostainer (Leica Microsystems, Bannockburn, IL) and primary antibodies directed against S100 protein (polyclonal and prediluted; Ventana, Oro Valley, AZ), mammaglobin (clone 304-1A5; dilution 1:250; Dako, Carpinteria, CA), p63 (clone 4A4; prediluted; Biocare), SOX10 (Clone BC34; Cat#ACI3099C 1:100; Biocare), CD117 (clone EP10, prediluted, BioSB), DOG1 (clone K9, ready to use, Leica Cat# PA0219), mucicarmine (cat#860-011, ready to use), and AR (clone BSB-4; prediluted, BioSB). Appropriate positive and negative controls were included. The immunohistochemical slides were reviewed by four MGH head and neck pathologists (A.S.F., I.L., M.N., and P.M.S.).