A case of benign schwannoma of the thoracic wall mimicking a malignant tumor.

A fist-sized tumor mainly locating in the right thoracic wall of a 73 year-old woman was found by ultrasonography and computed tomography, although a definitive diagnosis was not obtained because of the tumor extension to the abdominal cavity from the right internal thoracic wall, precluding biopsy. Angiography of the right eleventh intercostal artery demonstrated irregular tumor vessels, indicating malignant nature of the tumor. Therefore en-block resection of the tumor with the right eleventh rib was performed under a thoracotomy. Postoperative histopathological examination showed that the tumor was a benign schwannoma of Antoni type A. Since schwannoma is usually difficult to diagnose preoperatively without histopathological study, it is suggested that patients with schwannoma-like tumors, as represented by the present case, should be treated carefully to avoid excessive surgery including an extensive resection of the surrounding tissue.