Unusual metastasis of gastrointestinal stromal tumor misdiagnosed as anaplastic thyroid carcinoma

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumorsof thedigestive tract. Almost allGISTs express theKIT protein (CD 117), the product of the c-KIT protoncogene that is a transmembrane receptor for the stem cell factor (SCF or KIT ligand) with a tyrosine kinase domain. The tumorigenesis of GISTs involves mutations in the cKIT protoncogene, resulting in ligand-independent