Abstract

A histopathological study was done on 16 cases of malignant Schwannoma that were diagnosed at the Department of Pathology, Seoul National University during a period of 13 years, from January 1968 to December 1980. The 16 malignant Schwannomas were distributed in the mediastinum(5), extremities(4), abdominal cavity(2), retroperitoneum(1), etc. The peripheral nerve of origin was identified in four cases, and these were sciatic(2), femoral(1) and musculocutaneous(1). In two cases, electron microscopy was done and the Schwann cell origin was strongly supported by the ultrastructual findings of the tumors showing basement membranes, interdigitated intercellular junction and desmosomes. Histopathological features on malignant Schwannoma were characterized by mesodermal elements that were intermingling with Schwannian elements, such as cartilage, osteoid and rhabdomyoblasts. Two cases of malignant Schwannoma revealed eosinophilic granular cells in the midst of the tumor tissue. These cells demonstrated secondary lysosome in the cytoplasm electronmicroscopically.