PROLIFERATIVE ACTIVITY, ANGIOGENESIS, AND NECROSIS IN PERIPHERAL-NERVE SHEATH TUMORS - A QUANTITATIVE-EVALUATION FOR PROGNOSIS

Malignant peripheral nerve sheath tumors (MPNSTs) are distinguished fr om a control group of typical benign schwannomas and neurofibromas on the basis of a set of quantitatively evaluated parameters, ie., the ce ll density; the number of mitoses and apoptotic bodies; the nuclear ar ea and shape; the number and absolute and relative areas of silver-sta ining nucleolar organizer regions; necrosis; and angiogenesis. Only th e extent of tumor necrosis, the mitotic rate, and the parameters relat ed to silver-staining nucleolar organizer regions discriminate between less aggressive MPNSTs (disease-free patients after 4 years of follow -up) and more aggressive MPNSTs (with recurrences or metastases during the first 4 years of follow-up).