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Discussion
This series of meningiomas contained 13 tumors from 9 patients with more than one
meningioma, in whom there was no evidence of NF2. Therefore, the frequency of multiple
meningiomas andlor meningiomatosis in our study is 7.6% (9/119). This is in the same
range, between 4.5% and 10.5%, with other published series since the introduction of CT
scanning (Domenicucci et a!., 1989 and cited references). No differences could be observed
between these multiple meningioma Cases and the sporadic cases in all factors investigated
in this study, in accordance with the findings of Domenicucci et a!. (1989).
In agreement with previous reports all cytogenetically abnormal meningiomas, except
tumor 81, showed a hypodiploid karyotype, with loss of (parts of) chromosome 22 as the
most common aberration. FISH analysis performed in the second half of this study suggested
that the % of meningioma with loss of chromosome 22 was higher than detected by
cytogenetic andlor LOH studies. This is in support with a postulated role of chromosome 22
as the primary event in the development of (the majority of) meningiomas. In spite of this,
other changes involving chromosomes 1, 6, 11, 13, 14, 18, 19, X, and Y were also
frequently found. These observations corroborate and extend previous findings (Katsuyama
et a!., 1986; AI Saadiet aI., 1987; Casalone et a!., 1987; Maltby et a!., 1988; Rey et a!.,
1988; Logan et a!., 1990; Vagner-Capodano et ai., 1993; Biegel et ai., 1994). The most
consistent aberrations described in many papers are those of chromosome 1 with changes of
both the p- and q-arm and of chromosome 14. When the non-22 chromosomal aberrations
found in our series were independently compared with the histological grade of the tumors,
all these changes were predominantly observed in grade" and III tumors. Therefore, it is
difficult to unmask specific changes that underlie progression or a more anaplastic histology.
The association between abnormalities of chromosomes 1 and 14 and a more malignant
histOlogy was also found by Doney et a!. (1993). In addition, they observed that loss of
14q24-32 is the smallest region of overlap on chromosome 14. Interestingly we found
reciprocal trallSlocations with chromosome 14 both in band 14qll-12 in two meningiomas
(tumors 14 and 86). In tumor 86 it is the only cytogenetic abnormality found and this case
showed a benign histopathology. Changes concerning chromosome 6 were recently reported
to be the most common secondary alteration in pediatric meningiomas (Biegel et al., 1994).
The frequent involvement of chromosome 6 was also found by us but our tumors were all
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