Sigmoid colon Schwannoma simulating colon cancer

Area of Science:

• Gastroenterology
• Surgical Oncology
• Pathology

Background:

• Schwannomas are rare gastrointestinal tumors, accounting for 2-6% of all gastrointestinal tumors.
• Approximately 12% of gastrointestinal schwannomas occur in the small and large intestines.

Observation:

• An 87-year-old woman presented with epigastric pain and dyspepsia.
• CT scan and colonoscopy revealed a neoplastic process in the sigmoid colon.
• Laparoscopic sigmoidectomy was performed, with histological examination confirming a schwannoma.

Findings:

• Schwannomas are submucosal lesions, making endoscopic biopsy challenging as it typically samples only the mucosa.
• Differential diagnosis includes gastrointestinal stromal tumors (GIST) and leiomyomas.
• Immunohistochemistry is crucial: positive for S-100 and negative for C-KIT, CD-34, actin, and desmin aids in differentiating schwannoma from GIST and leiomyoma.

Implications:

• Accurate diagnosis of gastrointestinal schwannoma is difficult due to nonspecific radiological findings and challenges with endoscopic biopsies.
• S-100 positive immunohistochemistry in histological studies is essential for confirming schwannoma diagnosis.
• Understanding these diagnostic challenges is vital for appropriate patient management and treatment strategies.