Gastrointestinal stromal tumor, uncommitted type, with monosomies 14 and 22 as the only chromosomal abnormalities.

Karyotypic analysis of a gastric stromal tumor with the histologic and immunohistochemical features of a malignant, uncommitted lesion revealed clonal monosomies of chromosomes 14 and 22. Such changes, together with loss of chromosomes 15 and 18, as well as structural rearrangements involved chromosome 1, have been previously reported in gastrointestinal stromal tumors with smooth muscle differentiation. We suggest that monosomies of chromosomes 14 and 22 are early events in the malignant transformation of the mesenchymal cell-originating gastrointestinal stromal tumors.