Mesenteric Fibrosis in Midgut Neuroendocrine Tumors: Functionality and Radiological Features

Area of Science:

• Oncology
• Radiology
• Pathophysiology

Background:

• Mesenteric fibrosis (MF) is observed in midgut neuroendocrine tumors (NETs) but its cause is unclear.
• MF affects some, but not all, NET patients with lymphatic involvement.
• This study investigated MF's relationship with carcinoid syndrome, 5-hydroxyindoleacetic acid (5-HIAA), and carcinoid heart disease (CHD).

Purpose of the Study:

• To assess the association between mesenteric fibrosis (MF) and clinical/radiological features in midgut neuroendocrine tumors (NETs).
• To identify predictors of MF in patients with midgut NETs.
• To explore the link between MF, tumor functionality, and the development of carcinoid heart disease (CHD).

Main Methods:

• Retrospective analysis of 81 patients with midgut NETs and mesenteric lymphatic metastases.
• Evaluation of imaging characteristics, Ki67 grading, 5-HIAA levels, tumor functionality, and CHD development.
• Multivariate analysis to identify independent predictors of MF.

Main Results:

• Mesenteric fibrosis (MF) was present in 54% of patients.
• MF was significantly associated with mesenteric vessel encasement, hepatic metastases, and tumor functionality.
• Elevated urinary 5-hydroxyindoleacetic acid (5-HIAA) ≥395 µmol/day, age, and largest lymphatic metastasis size were independent predictors of MF.
• MF showed a trend towards association with functionality and CHD, and was linked to decreased time to CHD development in functional midgut NETs.

Conclusions:

• Mesenteric fibrosis (MF) in midgut NETs is significantly associated with metastatic patterns and tumor functionality.
• The link between MF, elevated 5-HIAA, carcinoid syndrome, and potential CHD development suggests a common pathophysiological pathway.
• Further research may elucidate mechanisms similar to endocardial fibrosis.