Incidental Schwannoma Identified During Laparoscopic Appendectomy for Acute Appendicitis: a Case Report.

Introduction: Schwannomas are benign neurogenic tumors that make up less than 1 percent of all gastrointestinal tumors. Schwannoma can occur along peripheral nerves anywhere throughout the body. Gastrointestinal schwannoma is relatively rare and most commonly occurs in the stomach, small intestine, and colon, respectively. There have only been a handful of case reports describing appendiceal schwannomas. Approximately 30-50 percent of appendicular tumors show clinical symptoms and signs similar to those of appendicitis.

Case Report: A 36-year-old male presented initially for right lower quadrant pain of one day duration. He denied any other associated symptoms. CT imaging of abdomen and pelvis showed a fluid-filled and dilated appendix with fat stranding consistent with appendicitis. He underwent laparoscopic appendectomy without complication. The pathology report showed a well-defined proliferation of bland uniform cells that contained small smooth nuclei and abundant foamy cytoplasm at the tip of the appendix. Scattered eosinophils were noted. These neoplastic cells were positive for S100 and negative for CD68, CD34, and CD117, most consistent with a schwannoma.

Discussion: Diagnosing appendiceal schwannoma pre-operatively is a challenging task due to the rare nature of the tumors and the lack of clinical features to separate it from other appendiceal pathology. Appendiceal schwannomas are benign but it is unclear if malignant transformation is possible if left untreated. While there are currently no agreed upon treatment guidelines for appendiceal schwannoma, it is currently thought that complete surgical resection is the best treatment while chemotherapy and radiotherapy are not effective.