Characterization of nuclear size, ploidy, DNA histogram type and proliferation index in 79 nerve sheath tumors.

The distribution values of ploidy, of the DNA histogram type, of the proliferation index and of the nuclear area are described in a series of 79 nerve sheath tumors including 7 traumatic neuromas, 55 primary and 9 recurrent benign schwannomas, 5 benign neurofibromas and 3 malignant tumors. The nuclear parameters were computed on Feulgen-stained nuclei (from archival formalin-fixed paraffin-embedded materials) by means of digital cell image analysis. The results show that 20-30% of benign nerve sheath tumors exhibit an abnormal nuclear DNA content (DNA index > 1.30). Such a feature was observed in the four groups of benign tumors, i.e. primary and recurrent schwannomas, neurofibromas and even traumatic neuromas. Aneuploid tumors exhibited triploid, hypertriploid or polymorphic DNA histogram types. The three malignant tumors under study were aneuploid. Lastly, the nuclear area and proliferation index measurements did not allow any clear distinction to be made between the four groups of benign tumors on the one hand, and between the benign and malignant tumors on the other.