Abnormalities of chromosome 22 in meningiomas and confirmation of the origin of a dicentric 22 by in situ hybridization.

We report three cases of meningioma. Case 1 had a dicentric chromosome number 22 resulting in partial monosomy for a portion of the q-arm, i.e., 46,XX,idic(22)(pter-->q11.2::q11.2-->pter) and 46,XX,psu dic(22)(pter-->q11.2::q11.2-->pter), which was the sole clonal abnormality. The origin of the dicentric chromosome from 22 was confirmed by in situ hybridization studies, using biotin-labeled alpha centromeric DNA probes for the acrocentric chromosomes. Case 2 had two distinct clonal abnormalities: deletion of 22q and monosomy of 22. Case 3 also had a deleted 22q.