In terms of their clinical and histopathologic presentation, neuroendocrine gastrointestinal tumours constitute an extremely diversifed group of malignancies and thus are difficult to diagnose. Late and often accidental diagnosis means a multistage therapeutic process. The authors present the case of a 78-year-old female patient with clinical symptoms of visceral perforation followed by diffuse peritonitis. The patient was immediately operated. Intraoperative presentation revealed annular narrowing of the intestinal lumen by a tumour located in the cecum just above Bauhin's valve. The free tenia was microperforated in the described lesion area and had been the primary cause of diffuse fibrinous and pyogenic peritonitis. In addition, choleliths were found in the gallbladder. Right hemicolectomy with regional lymphadenectomy and cholecystectomy were performed. No postoperative complications. Histopathologic examination of resected specimen returned carcinoma neuroendocrinale. The authors argue, that the uncommon clinical course and circular, closing growth of the small cecum-located tumour with coincident perforation may originally suggest non-epithelial disease background.