Schwannoma of the Appendix Orifice

Abstract

Schwannomas are rare mesenchymal tumors. They are usually diagnosed incidentally during endoscopic or diagnostic imaging for another reason. Malignant transformation is rare. In this case report, we present an incidental schwannoma protruding through the appendiceal orifice diagnosed during endoscopy. A healthy 56-year-old female underwent a surveillance colonoscopy for family history of colorectal cancer. A prominent and edematous appendiceal orifice was noted, and the area was aggressively biopsied. Histopathological assessment revealed a benign schwannoma. Computerized topography was unremarkable. Subsequently, the patient underwent a right hemicolectomy. Patient is scheduled to undergo routine surveillance in three years. Grossly, schwannomas are white, encapsulated, and well-circumscribed lesions that stain strongly positive for S100, GFAP, and CD57. Histologically, schwannomas demonstrate spindle cell proliferation. Several imaging modalities have been utilized in the diagnosis and management of mesenchymal neoplasms. Despite the benign nature of the diagnosis, complete surgical resection with clear margins remains the gold standard management strategy. Our case highlights the presence of a relatively uncommon tumor in an unusual anatomical location.

Schwannoma of the Appendix Mimicking a Metastatic Breast Cancer

“…Schwannoma is a rare mesenchymal tumor affecting the gastrointestinal tract, primarily observed in the stomach and often diagnosed incidentally. 10 Appendiceal schwannoma, an exceptionally rare variant, has been documented in only 15 reported cases in the existing literature, and definitive characteristic findings are yet to be established. 11 Clinical presentations vary, ranging from asymptomatic cases to appendicitis-like abdominal pain.…”

“…These findings are sufficient to confirm the diagnosis in the absence of KIT positivity and smooth muscle markers. 10 While schwannoma andon GIST have similar histological findings in that they both demonstrate a spindle-like proliferation, they have distinct immunohistochemistry staining. Greater than 95% of GISTs express c-Kit (CD117), CD34 (70%), and H-caldesmon (80%).…”

“…Greater than 95% of GISTs express c-Kit (CD117), CD34 (70%), and H-caldesmon (80%). 10 Levy et al described the radiological features of histopathologically proven schwannomas as well-defined homogeneously attenuating mural masses on CT. They lack the poor prognostic factors seen typically in gastrointestinal stromal tumors such as low attenuating haemorrhage, necrosis, or degradation within the tumor.…”

Appendiceal schwannoma presenting as acute appendicitis

“…Schwannomas are mainly slow-growing benign tumors that originate from Schwann cells arising from the peripheral nerve sheath. These tumors could be found wherever peripheral nerves are seen, and usually affect the nerves in the head, neck, and flexor surfaces of the extremities [1] . Schwannomas are rare in the gastrointestinal tract; account for 2%-6% of all submucosal tumors of the intestine, and stomach is the most common site (60%-70%) [4] .…”

“…Schwannomas are benign tumors derived from the Schwann cells of the nerve sheath. These neoplasms usually affect the nerves in the head, neck, and flexor surfaces of the extremities [1] . Gastrointestinal schwannomas are uncommon and account for 2%-6% of all submucosal neoplasms of the gastrointestinal tract [ 2 , 3 ].…”