Non-random trisomies of chromosomes 5, 8 and 12 in the prolactinoma sub-type of pituitary adenomas: Conventional cytogenetics and interphase fish study

Specimens from 53 pituitary adenomas (PAs), including 17 NFPA, 16 PRL-, 9 A CTH-, 9 GH- and 2 TSH-secreting tumors, underwent cytogenetic analysis by t he direct and short-term culture methods. Only 8 tumors(15%) appeared to ha ve an abnormal karyotype, To increase the resolution of cytogenetic analysi s, direct preparations from 31 PAs were investigated by interphase FISH wit h probes specific for chromosomes 5, 8, 12 and X, for which gain in pituita ry tumors has been reported. Of these 31 PAs, 17 (54.8%) had an abnormal do sage of one or more of the 4 chromosomes tested. Separate or combined triso mies of chromosomes 5, 8 and IZ were found in 10/10 prolactinomas and in 4/ 9 NFPA, whereas the combined loss of chromosomes 5 and 8 was observed in 1/ 6 ACTH- and 1/6 OH-secreting PAs. Present and earlier data on 23 PAs showed that tumors with the highest frequency of abnormal karyotypes revealed by cytogenetics and/or interphase FISH were PRL (78%), followed by NFPA (26%) and GH (18%), Recurrent structural rearrangements affecting chromosomes 1, 3 and 12 were also identified in prolactinomas, which therefore appear to b e the only pituitary adenoma sub-type with a defined trend of tumor-specifi c chromosomal changes. Cytogenetic and FISH analyses of different pituitary tumor sub-types indicate that they may harbour genetically distinct lesion s, Int. J, Cancer 86: 344-350, 2000, (C) 2000 Wiley-Liss, Inc.