<prompt> All are seen in carcinoid syndromeDiarrhoeaConstipationLiver metastasis5-HT secretion  <response>: Carcinoid syndrome is a paraneoplastic syndrome comprising the signs and symptoms that occur secondary to carcinoid tumors. The syndrome includes flushing and diarrhea, and less frequently, hea failure, vomiting and bronchoconstriction. It is caused by endogenous secretion of mainly serotonin and kallikrein. Ref: Internet sources 