PRIMARY PULMONARY TUMORS OF NERVE SHEATH ORIGIN

Primary intrapulmonary tumours of nerve sheath origin are extremely ra re. We describe the clinicopathological features of four such peripher al nerve sheath tumours, two benign and two malignant. Of the benign t umours, one was a typical schwannoma and the other an ancient or degen erated schwannoma. The typical schwannoma was endobronchial in origin, diagnosis being established by small bronchoscopic biopsy. The histol ogical diagnosis of malignant peripheral nerve sheath tumour required immunohistochemical and/or ultrastructural evidence of nerve sheath di fferentiation. One malignant tumour arose in a patient with Von-Reckli nghausen's disease. Both malignant tumours behaved aggressively with t he development of multiple intrapulmonary metastases, despite the mark edly different histological appearance of the two tumours. Flow cytome tric analysis of nuclear DNA content was performed on the four tumours , all of which showed a diploid DNA profile.