SCHWANNOMA (NEURILEMOMA) WITH MALIGNANT TRANSFORMATION A RARE, DISTINCTIVE PERIPHERAL-NERVE TUMOR

Malignant transformation of a schwannoma (neurilemoma) is an exceeding ly rare event. We describe two cases with such change and review the r eported purported examples. The tumors in our patients involved a fing er and pelvis. Sex, age, and clinical follow-up were available for onl y the second case, involving a 31-year-old man who died with recurrent and metastatic tumor. Seven acceptable cases were found in the litera ture. Analysis of the nine cases of schwannoma with malignant transfor mation showed no sex predilection, but revealed a tumor differing sign ificantly from conventional malignant peripheral nerve sheath tumors. The mean age (56 years) was two decades older, no patient had neurofib romatosis, in four cases there was a years-long history of an antecede nt mass, and in none of the cases was the malignant component an inter lacing, fasciculated spindle-cell tumor. Rather, the malignant compone nt was commonly purely epithelioid (seven of nine cases). In the two o ther cases, cells of the malignant component had neuroepithelial featu res. The prognosis for patients with schwannomas undergoing malignant change is poor. Five of eight patients with follow-up (62%) died of di sease with either residual (one patient) or metastatic tumor (four pat ients).