A rare very aggressive neuroendocrine neoplasm with the presence of nodular mass(es) arising from the neck, fundus or body of the gallbladder or by diffuse thickening of the gallbladder wall. Patients may be asymptomatic (diagnosed incidentally after surgical resection of the gallbladder) or may present epigastric pain, abdominal mass and/or non-specific symptoms, such as nausea, jaundice, flushing, cough, wheezing, ascites. Paraneoplastic syndromes such as Cushing syndrome, acanthosis nigricans, bullous pemphigoid, dermatomyositis and the Leser-Trelat sign may be associated. [from
SNOMEDCT_US]