Hepatocellular carcinoma arising from ectopic liver tissue in the spleen producing insulin-like growth factor II.

We report a case of splenic tumor associated with severe hypoglycemia. The patient was a 69-year-old man with a large splenic tumor. He had suffered from relapsing hypoglycemic attacks and the lowest serum glucose level (4 mg/dl). He died 34 months after the onset of symptoms of left abdominal pain. Autopsy revealed large tumors in the spleen, 3 medium sized tumors in the lungs, and several small tumors in the liver. Microscopic studies of the splenic tumors revealed a hepatocellular carcinoma which showed a strongly positive reaction against anti-PIVKA-II and anti-"hepatocyte" antibodies. Several bile ductules thought to be heterotopic remnants of the liver tissues were found in the capsule of the spleen, adjoining the splenic tumor. It was suggested that the tumor originated from one of these ductules. Electron microscopic analysis showed numerous endocrine-like granules of every tumor cell, and 87-165 times stronger mRNA expression of insulin-like growth factor-II was measured in the tumor tissues when compared with normal liver tissue. Owing to these results, we believe that this is the first report of hepatocellular carcinoma that had developed from a liver tissue in the spleen.