Chromosomal Aberrations in Thymoma: Review of the Literature and Report of Five Additional Cases
AR Laury, V Nose, P Dal Cin. Brigham & Women's Hospital, Boston
Background: Thymic tumors are rare, composing 0.1% of all adult neoplasms, and among them thymomas, a benign lesion, are the most common. Although cytogenetics of thymoma have been reported only as infrequent case reports, chromosome 6 seems to be the most frequently involved chromosome.
Design: We reviewed our electronic reporting system (PowerPath) for in-house cases of thymoma with cytogenetic reports between December 2004 and June 2008. Consult cases, tissue submitted from outside hospitals, and thymic carcinomas were excluded, but biopsies, recurrent and metastatic thymomas were included. 61 cases of thymoma were identified; 31 were submitted for cytogenetic analysis, and 18 were successfully karyotyped.
Results: Of the eighteen karyotyped thymomas, abnormal karyotypes were identified in five. Three of the five cases had chromosome 6 aberrations, e.g. r(6) in two cases and an unbalanced rearrangement, der(1;6)(q10:q10), resulting in loss of the short arm (p) of chromosome 6. No rearrangements of chromosome 6 were detected by GTG-banding in the remaining two karyotypically abnormal thymomas.
Conclusions: Chromosome aberrations have been so far observed in 14 thymomas, including our 5 cases reported here, with chromosome 6 aberrations being relatively frequent (9 of 14 cases). Ring of one chromosome 6, r(6), is the most common abnormality encountered (4 of 8 cases) , followed by deletion of either the short arm (3 cases) or of the long arm (2 cases) . In summary, loss of 6p and 6q are the commonest findings in all subgroups of thymoma, and there is no correlation, thus far, with histologic subtype.
Cytogenetic Aberrations in Thymoma Current case
|2||76||F||AB||48-49,XX,+del(X)(q24), +i(5p), +?del(7) (q22), der(11)t(1;11) (q23;25), t(11;?) (p15;?),-18,+r|
|14||46||M||B3||45-52,-X,Y,psu dic(11;1) (p15;p11),complex karyotype[cp15]|
Tuesday, March 10, 2009 9:30 AM
Poster Session III # 123, Tuesday Morning