Loss of <scp>YAP1</scp> C‐terminus expression as an ancillary marker for metaplastic thymoma: a potential pitfall in detecting <i>YAP1::MAML2</i> gene rearrangement

Abstract

YAP1 C-terminus immunohistochemistry is a highly sensitive and specific ancillary marker that distinguishes metaplastic thymoma from its mimics. BA-FISH assays could not effectively detect YAP1::MAML2 fusions due to the proximity of the two genes. Loss of YAP1 C-terminus expression is a reliable surrogate for the detection of YAP1::MAML2 fusions in metaplastic thymoma.