Liver Mass: When in Doubt Think Carcinoid or Islet Cell Carcinoma

Abstract

Few differentials for liver lesions include hepatocellular carcinoma, cholangiocarcinoma, hepatic adenoma, hepatic hemangioma, hepatic cysts and metastases. Carcinoids and islet cell carcinomas are normally not in the differential due to their rarity in comparison to the other conditions. Since these tumors are slow growing, the liver has time to adapt; hence patients present with minimal symptoms and large masses on imaging. It is imperative to have both carcinoid and islet cell carcinoma on top of the list for differentials when an incidental asymptomatic liver lesion is seen. 66-year-old male previously treated with ABVD for Hodgkin's lymphoma in 1999 presented with back pain. He denied flushing, chills, fever, diarrhea and lightheadedness. Physical exam was benign. Pertinent laboratory data revealed creatinine of 3.1, potassium of 5.3 and mildly elevated alkaline phosphatase. Three-phase CT of the abdomenshowed two masses in the liver (Figure 1): a 22 cm mass in the right lobe and a 2.5 cm mass in the left lobe. There was also a 4 cm mass in the right kidney. Initially, the liver lesions were thought to be metastases from the kidney. However, biopsy of the kidney mass revealed renal cell carcinoma while biopsy of the largest liver lesion was consistent with neuroendocrine carcinoma. To classify the etiology of the neuroendocrine carcinoma, whole body imaging with SPECT and octreotide scan was performed. A large 19 cm mass and two small lesions were noted in the right lobe of the liver. Lymph node adjacent to the third portion of the duodenum demonstrated abnormal uptake and it was presumed that the duodenum was the primary source of the neuroendocrine carcinoma. Lesions in the liver were likely metastases. The patient was treated with an ablation for renal cell carcinoma and started on somatostatin for neuroendocrine carcinoma of the duodenum. Differentiating carcinoids and islet cell carcinomas poses a diagnostic challenge for pathologists as both entities share the same histology and often immune staining can yield mixed results. It is very important as specialists to have both these diseases in the differential and make the correct diagnosis by taking into consideration the primary site involved along with the presence of 5-HIAA. Even with risk factors for other etiologies, a biopsy should be performed with further testing as indicated to make the correct diagnosis. Identifying the correct diagnosis further helps optimize treatment.2368 Figure 1. Aymptomatic Liver Lesion