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Table 2.
Comparison of FISH, cytogenetic and LOn techniqnes for detection of
(paltinl) loss of chl'omosome 22 in meningioma
Number of tumors (%)
Technique
FISH
Cytogenetics
LOH
Total* Disomy 22 (partial) loss of 22 not evaluable
30 5 (16.7%) 25 (83.3%) o
54 20 (37%) 34 (63%) o
(13X: normal)
(lOX: -22 only)
( 7X: other abn.) (24X: -22 and other
aim.)
69 13 (18.8%) 50 (72.5%) 6 (8.7%)
* The following tumors were excluded for rea~ons described in the result section, FISH: 1:33, 177; Cytogenetics:
10, 16, 133, 176. 177; LOH: 10, 133.
The results of cytogenelic analysis of 59 meningiomas cultured for less than 50 days
are shown in table 3. Longer culture times usually resulted in normal karyotypes, which was
probably due to outgrowth of normal cells initially present in low numbers in the cultures.
This was seen also when repeated cytogenetic analysis of meningiomas with an altered
karyotype resulted in normal karyotypes in the course of time (data nol shown). Thirteen
meningiomas showed a normal or non-clonal karyotype and in 41 cases clonal chromosomal
abnormalities were found. Twenty three of the cases with chromosomal abnormalities showed
::;; 2 changes, including chromosome 22 aberrations in 17 cases. In eighteen meningiomas
more than 2 chromosomal abnormalities, incuding chromosome 22, were identified. In at
least 12 meningiomas chromosome 22 was involved in structural abnormalities. These are
further discussed below. Partial or complete loss of chromosome 22 was the most frequently
observed abnormality (63%) in this series of meningiomas. In addition to this other
chromosomes also showed non random abnormalities in all or sublines of the cells. Of these,
chromosomes I (27.7%), 6 (13%), II (13%), 13 (14.8%), 14 (18.5%), 18 (13%), 19
(24.1 %), X (20.5%), and Y (20%) were most of len involved (table 3). Complete or partial
loss of these chromosomes was the predominant abnormality.
80