Adenocarcinoid of the liver arising within an area of hamartoma with predominant bile duct component.

Malignant transformation in bile duct hamartomas has been previously reported in very rare instances. Here, we describe a unique case of a neuroendocrine tumor of the liver arising within an area of unusually large hamartoma with predominant bile duct component, hitherto unreported and distinct from the conventional von Meyenburg complex. The tumor was apparently secreting gastrin and chromogranin, with associated gastrinoma syndrome over several years. The histologic picture was reminiscent of a moderately differentiated adenocarcinoid, with positive mucin staining in a signet ring pattern. Tumor cells showed positive staining for neuron-specific enolase, chromogranin A, gastrin, and serotonin. Staining for pancreatic hormone peptides was negative. Resection of the tumor was apparently curative, with complete resolution of the patient's symptoms.