Background: Gastrointestinal schwannoma is not a common type of tumor, and lesions
originating from the appendix are extremely rare. Herein, we report a patient with appendiceal schwannoma
characterized by lymph node swelling.
Case Report: A 67-year-old male patient who had diabetes complained of weight loss. A computed
tomography scan revealed a mass in the right side of the pelvic cavity. Moreover, a contrast-enhanced
computed tomography scan showed perilesional lymph node swelling measuring up to 28
mm. A low-intensity mass was observed on T1-weighted imaging, heterogeneous high-intensity
mass on T2-weighted imaging, and restricted diffusion on diffusion-weighted imaging. There were
no abnormal findings on colonoscopy. Based on a preoperative examination, a differential diagnosis
of either appendiceal schwannoma, carcinoid, or gastrointestinal stromal tumor was considered.
During surgery, a large appendiceal mass and multiple swollen perilesional lymph nodes were observed.
Therefore, ileocecal resection and D3 lymph node dissection were performed. Pathological
and immunohistochemical analyses confirmed the diagnosis of appendiceal schwannoma. There
were numerous swollen lymph nodes in the mesenteric region. The lymph nodes revealed reactive
lymphoid hyperplasia, with enlarged follicles of various sizes and shapes with an irregular distribution.
Almost all lymphocytes, except those at the germinal centers, were small.
Conclusion: Gastrointestinal schwannoma is characterized by lymph node swelling. Appendiceal
schwannoma may have characteristics, including peritumoral lymph node swelling, similar to other
types of gastrointestinal schwannoma such as that in the stomach. Thus, this characteristic can be a
diagnostic clue for appendiceal schwannoma.