IHC staining for the detection of TFE3 was performed using a goat polyclonal antibody for TFE3 (sc-5958, Santa Cruz Biotechnology, Santa Cruz, CA, USA) and the Envision detection kit (Dako, Carpinteria, CA, USA) in 76 suspected Xp11.2 RCC. The detailed procedures of immunostaining was carried out as mentioned in previous study29 (link).
All slides were examined and scored by two pathologists, who were blinded to all clinical data, in an open discussion. The interpretation of immunoreactivity for TFE3 was evaluated as previously reported20 (link)30 (link). Tumors scored as positive for TFE3 demonstrated nuclear immunoreactivity that was readily apparent at low-power magnification (×4 objective). These cases were subdivided into moderately (2+) and strongly (3+) positive on the basis of the intensity of labeling. Weak/equivocal nuclear immunoreactivity (1+) for TFE3, demonstrating nuclear immunoreactivity was subtle at low magnification and typically required higher magnification to be appreciated, was considered as negative. Cytoplasmic immunoreactivity was ignored because native TFE3 and its fusion proteins are known to localize to the nucleus31 (link).
All slides were examined and scored by two pathologists, who were blinded to all clinical data, in an open discussion. The interpretation of immunoreactivity for TFE3 was evaluated as previously reported20 (link)30 (link). Tumors scored as positive for TFE3 demonstrated nuclear immunoreactivity that was readily apparent at low-power magnification (×4 objective). These cases were subdivided into moderately (2+) and strongly (3+) positive on the basis of the intensity of labeling. Weak/equivocal nuclear immunoreactivity (1+) for TFE3, demonstrating nuclear immunoreactivity was subtle at low magnification and typically required higher magnification to be appreciated, was considered as negative. Cytoplasmic immunoreactivity was ignored because native TFE3 and its fusion proteins are known to localize to the nucleus31 (link).
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