Primary Hepatic Neuroendocrine Tumor with Unusual Thyroid Follicular-Like Morphologic Characteristics

We describe a primary hepatic neuroendocrine tumor of a 57-year-old Thai woman who presented in 2004 with a suspicious mass in the left hepatic lobe. She underwent left hepatectomy for the 10.5-cm mass, called intermediate grade neuroendocrine carcinoma of unknown origin , likely metastatic . The tumor recurred in 2007, then called recurrent primary hepatic neuroendocrine tumor (PHNET), and the patient underwent liver transplant. Because of similarity between the neuroendocrine tumor and a thyroid tumor—specifically, follicular-like characteristics—immunohistochemical stains for thyroglobulin, TTF1, and calcitonin were performed. However, all were negative. All imaging studies revealed no evidence of a primary lesion other than the liver mass. In 2008, the patient’s liver transplant failed because of ischemic cholangiopathy, and she underwent a second liver transplant. Seven years later, in 2015, she presented with metastatic neuroendocrine tumor of intermediate grade to the lung, consistent with metastatic PHNET. She underwent left upper-lobe wedge resection to remove the tumor. The patient is alive with no evidence of disease at 13 years after initial diagnosis. This rare variant of PHNET had thyroid-like morphologic characteristics but there is no evidence of primary thyroid tumor or thyroid markers in the primary and recurrent hepatic tumors and lung metastasis.