Abstract
An 82-year-old man with a positive fecal occult blood test but no abdominal symptoms was admitted to our hospital. Computed tomography revealed a 25-mm, enhancing mass in the mid-appendix, suggesting an appendiceal tumor. The patient underwent laparoscopic partial cecectomy. Intraoperative, rapid frozen-section biopsy showed a benign mesenchymal tumor with clear resection margins. Typical Verocay bodies composed of palisading nuclei and alternating regions of hyper- and hypocellularity showing Antoni A and Antoni B patterns were observed on histopathologic study of the tumor. Immunohistochemical staining was strongly positive for S-100 protein and negative for c-kit, CD34, and SMA. A diagnosis of appendiceal schwannoma was made. There has been no evidence of recurrence during 3 years of postoperative follow-up. Appendiceal schwannoma is a rare tumor derived from Schwann cells in Auerbach's plexus. Preoperative diagnosis is very difficult because the clinical features are nonspecific and often mimic malignancy. This is a rare case with a tumor located in the appendix, as very few cases have been reported in the literature in Japan.
