title: Absence of gene mutations in KIT-positive carcinoma showing thymus-like elements of the thyroid.
abstract: KIT, a tyrosine kinase receptor protein encoded by the proto-oncogene c-kit, is overexpressed in human neoplasms such as gastrointestinal stromal tumors and thymic squamous cell carcinoma. However, the role of KIT expression and mutations in carcinoma showing thymus-like elements is not fully understood. In the current study, 8 cases of carcinoma showing thymus-like elements were reported, and immunohistochemical staining with KIT and CD5 was performed. Mutation analyses in the juxtamembrane domains (exons 9 and 11) and in the tyrosine kinase domains (exons 13 and 17) were performed on KIT-positive samples using polymerase chain reaction and direct DNA sequencing. KIT- and CD5-positive stainings were observed in all 8 cases. However, none of the tested samples showed mutations in any of the 4 exons. The primary carcinoma showing thymus-like elements of the thyroid frequently expresses KIT and CD5 proteins; similar to thymic squamous cell carcinoma, the overexpression of KIT does not necessarily indicate a gene mutation in this tumor. KIT, along with CD5, could be a useful marker for the difficult diagnosis of carcinoma showing thymus-like elements, which should be added to the list of KIT-positive neoplasms.
authors.affiliation: Department of Pathology, Tianjin Medical University Cancer Institute and Hospital and Key Laboratory of Cancer Prevention and Therapy, Tianjin 300060, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Pan
authors.forename: Xiulan
authors.initials: X
authors.lastname: Zhao
authors.forename: Jilong
authors.initials: J
authors.lastname: Yang
authors.forename: Jingyu
authors.initials: J
authors.lastname: Deng
authors.forename: Zhongli
authors.initials: Z
authors.lastname: Zhan
authors.forename: Ye
authors.initials: Y
authors.lastname: Luo
authors.forename: Qi
authors.initials: Q
authors.lastname: Li
authors.forename: Yan
authors.initials: Y
authors.lastname: Guo
authors.forename: Qiongli
authors.initials: Q
authors.lastname: Zhai
authors.forename: Baocun
authors.initials: B
authors.lastname: Sun
mesh_terms: D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor / Q000378:metabolism; D002294:Carcinoma, Squamous Cell / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D004252:DNA Mutational Analysis; D004273:DNA, Neoplasm / Q000032:analysis; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009154:Mutation; D037981:Neck Dissection; D000090063:Proto-Oncogene Mas; D019009:Proto-Oncogene Proteins c-kit / Q000378:metabolism*; D013950:Thymus Gland / Q000378:metabolism / Q000473:pathology*; D013964:Thyroid Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D013965:Thyroidectomy
chemical_list: D014408:Biomarkers, Tumor; D004273:DNA, Neoplasm; C000715470:MAS1 protein, human; D000090063:Proto-Oncogene Mas; D019009:Proto-Oncogene Proteins c-kit