Nonepithelial Neoplasms of the Pancreas, Part 2: Malignant Tumors and Tumors of Uncertain Malignant Potential From the Radiologic Pathology Archives.

Almost all neoplasms of the pancreas are derived from pancreatic epithelial components, including the most common pancreatic mass, primary pancreatic ductal adenocarcinoma (PDAC). Nonepithelial neoplasms comprise only 1%-2% of all pancreatic neoplasms. Although some may arise directly from intrapancreatic elements, many originate from mesenchymal, hematopoietic, or neural elements in the retroperitoneal peripancreatic space and grow into the pancreas. Once these tumors reach a certain size, it can be challenging to identify their origin. Because these manifest at imaging as intrapancreatic masses, awareness of the existence and characteristic features of these nonepithelial neoplasms is crucial for the practicing radiologist in differentiating these tumors from primary epithelial pancreatic tumors, an important distinction given the vastly different management and prognosis. In part 1 of this article, the authors reviewed benign nonepithelial neoplasms of the pancreas. This article focuses on malignant nonepithelial neoplasms and those of uncertain malignant potential that can be seen in the pancreas. The most common malignant or potentially malignant nonepithelial pancreatic tumors are of mesenchymal origin and include soft-tissue sarcomas, solitary fibrous tumor, and inflammatory myofibroblastic tumor. These tumors commonly manifest as large heterogeneous masses, often containing areas of necrosis and hemorrhage. The clinical features associated with these tumors and the imaging characteristics including enhancement patterns and the presence of fat or calcification help distinguish these tumors from PDAC. Hematopoietic tumors, including lymphoma and extramedullary plasmacytoma, can manifest as isolated pancreatic involvement or secondarily involve the pancreas as widespread disease. Hyperenhancing paragangliomas or hypervascular metastatic disease can mimic primary pancreatic neuroendocrine tumors or vascular anomalies.

Prediction of the histopathologic findings of intrahepatic cholangiocarcinoma: qualitative and quantitative assessment of diffusion-weighted imaging.

OBJECTIVE: To correlate qualitative and quantitative diffusion weighted imaging (DWI) characteristics of intrahepatic cholangiocarcinoma (ICC) with histopathologic tumour grade and fibrosis content. METHODS: Fifty-one patients (21M/30F; mean age 61y) with ICC and MRI including DWI were included in this IRB-approved multicentre retrospective study. Qualitative tumour features were assessed. Tumour apparent diffusion coefficient (ADC) mean, minimum, and normalized (nADCliver) values were computed. Tumour grade [well(G1), moderately(G2), or poorly differentiated(G3)] and tumour fibrosis content [minimal(1), moderate(2), or abundant(3)] were categorized pathologically. Imaging findings and ADC values were compared with pathologic measures. Utility of ADC values for predicting tumour grade was assessed using ROC analysis. RESULTS: 51 ICCs (mean size 6.5±1.1 cm) were assessed. 33/51(64%) of ICCs demonstrated diffuse hyperintensity and 15/51(29%) demonstrated target appearance on DWI. Infiltrative morphology (p=0.02) and tumour size (p=0.04) were associated with G3. ADCmean and nADCmean of G3 (1.32±0.47x10-3 mm2/sec and 0.97±0.95) were lower than G1+G2 (1.57±0.39x10-3 mm2/sec and 1.24±0.49; p=0.03 and p=0.04). ADCmean and nADCmean were inversely correlated with tumour grade (p<0.025). No correlation was found between ADC and tumour fibrosis content. AUROC, sensitivity and specificity of nADCmean for G3 versus G1+G2 were 0.71, 89.5% and 55.5%. CONCLUSION: ADC quantification has reasonable accuracy for predicting ICC grade. KEY POINTS: • ADC quantification was useful for predicting ICC tumour grade. • Infiltrative tumour morphology and size were associated with poorly differentiated ICCs. • ADC values depended more on ICC tumour grade than fibrosis content. • Ability to predict ICC tumour grade non-invasively could impact patient management.

Spontaneous Regression of Hepatocellular Carcinoma with Multiple Lung Metastases: A Case Report and Review of the Literature.

Spontaneous regression of hepatocellular carcinoma (HCC) is a rare event. Here we present a case of spontaneous regression of metastatic HCC. A 53-year-old man with hepatitis C and alcoholic cirrhosis was found to have a large liver mass consistent with HCC based on its radiographic features. Imaging also revealed left portal and hepatic vein thrombosis, as well as multiple lung nodules concerning for metastases. Approximately 2 months after the initial diagnosis, both the primary liver lesion and the lung metastases decreased in size and eventually resolved without any intervention. Thereafter, the left hepatic vein thrombus progressed into the inferior vena cava and the right atrium, and the patient died due to right heart failure. In this case report and literature review, we discuss the potential mechanisms for and review the literature on spontaneous regression of metastatic HCC.

Nonepithelial Neoplasms of the Pancreas: Radiologic-Pathologic Correlation, Part 1--Benign Tumors: From the Radiologic Pathology Archives.

Solid and cystic pancreatic neoplasms are being recognized more frequently with increasing utilization and spatial resolution of modern imaging techniques. In addition to the more common primary pancreatic solid (ductal adenocarcinoma) and cystic neoplasms of epithelial origin, nonepithelial neoplasms of the pancreas may appear as well-defined solid or cystic neoplasms. Most of these lesions have characteristic imaging features, such as a well-defined border, which allows differentiation from ductal adenocarcinoma. Solid masses include neurofibroma, ganglioneuroma, leiomyoma, lipoma, and perivascular epithelioid cell tumor (PEComa). Schwannomas and desmoid tumors can be solid or cystic. Cystic tumors include mature cystic teratoma and lymphangioma. Lipoma, PEComa, and mature cystic teratoma can contain fat, and ganglioneuroma and mature cystic teratoma may contain calcification. Although these unusual benign neoplasms are rare, the radiologist should at least consider them in the differential diagnosis of well-defined lesions of the pancreas. The goal of this comprehensive review is to improve understanding of these rare primary pancreatic mesenchymal tumors.