Cytogenetic biclonality corresponding to multiphasic differentiation in an atypical thyroid adenoma.

Cytogenetic aberrations have been described in about 30% of benign thyroid tumors, but their role for tumorigenesis or progression has not yet been elucidated. We describe the cytogenetic analyses in a thyroid adenoma with two different clonal cytogenetic stemlines: 45,XX,der(1)t(1;14)(p13;q11.2-q(13),t(5;12)(q11.2;q24),del(9)(q12),- 10,der(11)t(11;?;19)(p15;q13),der(14)t(14;15)(q11.2-q13;q23),del(15)(q23 ), der(15)t(9;15)(q12;p10),der(19)t(10;19)(q11.2;q13)/46,X,?inv(x),?inv(3) (p21q29),t(3;8)(q26;q12). Histologic examination revealed an atypical follicular thyroid adenoma containing microfollicular, follicular, trabecular-solid, and oncocytic components. There may be a direct relation between the different cytogenetic stemlines and the histologic diversity of the tumor. Thyroid tumors with complex karyotypes involving the 19q13 breakpoint may represent advanced stages of karyotypic evolution and therefore warrant an extensive clinical follow-up.