Clinical signs of fibrosis in small intestinal neuroendocrine tumours

Background: In patients with small intestinal neuroendocrine tumours (SI-NETs), serotonin and other cytokines released from tumour cells may induce fibrosis, leading to carcinoid heart disease and abdominal fibrotic reactions. The aim of this study was to assess the prevalence, clinical complications and management of this reaction in the abdomen. Methods: This was a retrospective cohort study of patients with SI-NETs diagnosed between 1985 and 2015. Clinical data, outcomes, radiological findings, and surgical and radiological interventions were reviewed. Results: A total of 824 patients were diagnosed with SI-NETs in the study interval. Clinically significant abdominal signs and symptoms of fibrosis occurred in 36 patients. Of these, 20 had critically symptomatic central mesenteric fibrosis causing obstruction of mesenteric vessels, and 16 had retroperitoneal fibrosis causing obstructive uropathy with hydronephrosis. Extensive fibrosis causing mesenteric vessel obstruction and/or obstructive uropathy was more often associated with symptomatic and advanced disease encompassing lymph node metastases in the mesenteric root, para-aortic lymph node metastases, as well as liver metastases and peritoneal carcinomatosis. Palliative intervention in terms of superior mesenteric vein stenting or resection of central mesenteric metastases and/or percutaneous nephrostomy and J stent treatment was beneficial in the majority of the patients. Conclusion: Extensive abdominal fibrosis associated with clinically significant symptoms of intestinal ischaemia and/or obstructive uropathy was linked to advanced disease in patients with SI-NETs. Prompt recognition and minimally invasive intervention was effective in disease palliation.