Case report of carcinoid syndrome with multi-organ involvement.

Background: Carcinoid syndrome (CS) is a rare complication of neuroendocrine tumors (NETs). Characterized by cutaneous flushing, diarrhea, abdominal pain, and long-term risk for valvular heart disease, these components occur in a fraction of patients with advanced disease. Early recognition through history taking, physical and laboratory examination, and clinical imaging is paramount to successful management. Case Description: We report a case of CS in a 21-year-old male patient found to have a metastatic gastrointestinal, well differentiated (Ki67 <3%) NET. The patient presented with cutaneous flushing, diarrhea, abdominal pain, dyspnea, ascites, and peripheral edema. On imaging, he was found to have a massive left pleural effusion, innumerable enhancing hepatic lesions, mesenteric lymphadenopathy, and large-volume ascites. Cardiac imaging further showed severe tricuspid regurgitation and right heart failure. Biopsy of the enhancing hepatic lesions showed a grade 1 NET of gastrointestinal origin. Urine testing revealed markedly high serotonin metabolites. The patient was started on somatostatin analogues, which resulted in improved control of diarrhea and flushing. Thoracoscopic surgery improved pleural effusion accumulation, and recurrent abdominal ascites was treated with paracentesis when necessary. He was also referred to cardiothoracic surgery tricuspid valve replacement surgery. Conclusions: Our case illustrates the classic characteristics of CS as well as valvular heart disease supported by clinical imaging of the syndrome's involvement of multiple organ systems. These findings are important for physicians to recognize as early recognition of CS can lower the risk of long-term complications of carcinoid heart disease. Additionally, patients with limited access to healthcare may be at risk of later CS presentation.