Primary epithelioid malignant schwannoma of the lung.

This is the first documented report of a case of primary malignant nerve sheath tumor of the lung showing an epithelioid malignant schwannoma. A 55 year old Japanese female underwent lobectomy of the middle lobe of the right lung because of a large, rounded tumorous shadow found on chest X-ray film. Light microscopic examination of the neoplasm disclosed an epithelioid malignant schwannoma with foci having a spindle-cell sarcomatous pattern. The neoplastic cells were positive for S-100 protein and neuron specific enolase by the immunoperoxidase method. Transmission electron microscopy showed basement membrane-like material surrounding the neoplastic cells and long spacing collagens in the interstitial spaces. The patient died of a recurrent tumor in the right hemithorax 5 months after undergoing lobectomy. An autopsy revealed no primary site of the neoplasm outside the lung. Furthermore, there was no evidence of neurofibromatosis.