Snapshot A 32-year-old woman presents to the clinic with complaint of diarrhea for the past three months. She states that her diarrhea has been watery and not greasy, and she has not seen any blood in the toilet bowl. Upon further questioning, she states that she has also experienced wheezing and skin peeling on her hands and feet. On physical examination, the patient's face and neck appears as seen in the image. Introduction Overview carcinoid syndrome is a rare syndrome that is caused by the metastasis of carcinoid tumors that secrete high levels of serotonin (5-HT) treatment is usually with surgical resection or octreotide Epidemiology incidence rare, 1-2 cases per 100,000 individuals demographics most frequently in patients 50-70 years of age Pathophysiology metastasis of carcinoid tumors that produce serotonin carcinoid tumors most commonly located in the ileum and appendix (90%) login to view 3 more bullets Associated conditions medical conditions pellagra caused by niacin (vitamin B3) deficiency login to view 1 more bullet Presentation Symptoms common symptoms cutaneous flushing recurrent diarrhea login to view 1 more bullet abdominal cramps asthma-like wheezing Physical exam erythema pellagra skin lesions wheezing hepatomegaly from metastases pulmonary systolic and diastolic heart murmur cardiac involvement causes carcinoid heart disease login to view 2 more bullets Imaging CT indication localize the primary tumor assess extent of tumor spread and metastases In-111 octreotide scan indication localize the primary carcinoid tumor and recurrences Studies Labs measurement of urinary excretion of 5-HIAA best initial test urinary excretion of 5-HIAA ≥ 25 mg/day is diagnostic login to view 1 more bullet Differential VIPoma key distinguishing factor presents with WDHA syndrome login to view 3 more bullets may present with flushing similar to carcinoid syndrome, but no wheezing or right-sided heart murmurs are present Treatment Surgical surgical resection of tumor indications login to view 2 more bullets Medical octreotide or other somatostatin analog indications login to view 1 more bullet Complications Carcinoid heart disease incidence up to 50% of patients with carcinoid syndrome risk factors higher urinary levels of 5-HIAA associated with greater risk of progression of carcinoid heart disease treatment somatostatin analogs