Karyotypic characterization of papillary thyroid carcinomas

BACKGROUND. Cytogenetic studies performed in papillary thyroid carcinoma (P TC) identified chromosome 10q rearrangements with breakpoints at 10q11.2 as the most frequent aberrations in these tumors. In the current study, the a uthors aimed to identify other chromosomal abnormalities nonrandomly associ ated with papillary thyroid carcinomas. METHODS. Cytogenetic analysis was performed on 94 papillary thyroid carcino mas after short-term culture of the tumors sterile fragments. RESULTS. Clonal chromosomal changes were found in 37 tumors (40%). Structur al cytogenetic abnormalities were observed in 18 carcinomas. Chromosomes 1, 3, 7, and 10 were the most frequently involved in rearrangements. Pooled r esults of the breakpoints detected in these tumors, as well as those descri bed in the literature, allowed the authors to verify as the most common bre akpoint loci 1p32-36, 1p11-13, 1q, 3p25-26, 7q34-36, and 10q11.2. The corre lation between the karyotype features of the 94 PTCs and the histologic dat a revealed that some PTC follicular variants were characterized by chromoso mal aberrations commonly found in thyroid follicular adenomas: a del(11)(q1 3q13), a t(2;3)(q13;p35), and gains of chromosomes 3, 5, 7, 9, 12, 14, 17, and 20. In the tall cell PTC variant group, 4 of the 7 tumors presented clo nal cytogenetic changes, 3 (75%) of which were characterized by anomalies o f chromosome 2 that lead to a overrepresentation of the long arm of this ch romosome. Noted also in these series was an association between complex kar yotypes and tumors with poorly differentiated histiotypes. CONCLUSIONS. In this study, the authors report chromosome 1p32-36, 1p11-13, 3p25-26, and 7q32-36 as novel breakpoint cluster regions in PTC, and they suggest that there are cytogenetic changes preferentially associated with t he follicular and tall cell PTC variants. (C) 2001 American Cancer Society.