A Retrospective Analysis of Preoperative Evaluation and Surgical Resection for Metastatic Tumors of the Pancreas

Comments on and Illustrations of the EFSUMB CEUS Guidelines: Transabdominal and Endoscopic Ultrasound Features of Intrapancreatic Metastases and the Role of Multiparametric Imaging and EUS-Guided Sampling in Rare Pancreatic Tumors

A definite pathologic diagnosis of intrapancreatic metastasis is crucial for the management decision, i.e., curative or palliative surgery versus chemotherapy or conservative/palliative therapy. This review focuses on the appearance of intrapancreatic metastases on native and contrast-enhanced transabdominal ultrasound and endoscopic ultrasound. Differences and similarities in relation to the primary tumor, and the differential diagnosis from pancreatic carcinoma and neuroendocrine neoplasms are described. The frequency of intrapancreatic metastases in autopsy studies and surgical resection studies will be discussed. Further emphasis is placed on endoscopic ultrasound-guided sampling to confirm the diagnosis.

Isolated Pancreatic Metastases of Renal Cell Carcinoma-Clinical Particularities and Seed and Soil Hypothesis

A meta-analysis of 1470 isolated pancreatic metastases of renal cell carcinoma revealed, that, in addition to the unusual exclusive occurrence of pancreatic metastases and the favourable treatment results, the isPMRCC is characterised by further peculiarities of the clinical course: The lack of prognostic significance of volume and growth rate dependent risk factors and the independence of treatment results from standard or local resections. As an explanation for all these peculiarities, according to today's knowledge, a strong acting seed and soil mechanism can serve, which allows embolized tumour cells to grow to metastases only in the pancreas, and prevents them definitively or for years in all other organs. The good prognosis affects not only isolated PM, but also multi-organ metastases of the RCC, in which the additional occurrence of PM is also associated with a better prognosis. Genetic studies revealed specific changes in cases of PM of RCC: Lack of loss of 9p21.3 and 14q31.2, which are otherwise specific gene mutations at the onset of generalization, a low weight genome instability index, i.e., high genetic stability, and a low rate of PAB1 and a high rate of BPRM1 alterations, which signal a more favourable course. The cause of pancreatic organotropism in isPMRCC is still unclear, so only those factors that have been identified as promoting organotropism in other, more frequent tumour entities can be presented: Formation of the pre-metastatic niche, chemokine receptor-ligand mechanism, ability to metabolic adaptation, and immune surveillance.

Isolated Pancreatic Metastases of Renal Cell Cancer: Genetics and Epigenetics of an Unusual Tumour Entity

Isolated pancreatic metastases of renal cell carcinoma (isPMRCC) are a rare manifestation of metastatic renal cell carcinoma (mRCC) characterized by two peculiarities: (1). The definite or at least long-term exclusive occurrence of metastases in the pancreas and (2). an unusual low tumour aggressiveness with slow tumour progression and consecutive, good treatment results. According to current knowledge, the exclusive occurrence of pancreatic metastases is due to a highly specific and highly selective seed and soil mechanism, which does not allow metastases settlement outside the pancreas, and whose detailed genetic/epigenetic causes are not yet elucidated. Recent studies have shed light on some of the pathways involved for the protracted course of the disease and highlighted a special genetic profile (lack of loss of 9p, lower weight genome instability index, low frequency of BAP1 alterations, and a high frequency of PBRM1 loss), which deviates from the conventional mRCC profile. Finally, the question of the reasons for the long-term relative genetic stability of the involved cell clones, which is an essential prerequisite for a favourable prognosis, remains unanswered.

Malignant biliary obstruction due to metastatic non-hepato-pancreato-biliary cancer

Malignant biliary obstruction generally results from primary malignancies of the pancreatic head, bile duct, gallbladder, liver, and ampulla of Vater. Metastatic lesions from other primaries to these organs or nearby lymph nodes are rarer causes of biliary obstruction. The most common primaries include renal cancer, lung cancer, gastric cancer, colorectal cancer, breast cancer, lymphoma, and melanoma. They may be difficult to differentiate from primary hepato-pancreato-biliary cancer based on imaging studies, or even on biopsy. There is also no consensus on the optimal method of treatment, including the feasibility and effectiveness of endoscopic intervention or surgery. A thorough review of the literature on pancreato-biliary metastases and malignant biliary obstruction due to metastatic non-hepato-pancreato-biliary cancer is presented. The diagnostic modality and clinical characteristics may differ significantly depending on the type of primary cancer. Different primaries also cause malignant biliary obstruction in different ways, including direct invasion, pancreatic or biliary metastasis, hilar lymph node metastasis, liver metastasis, and peritoneal carcinomatosis. Metastasectomy may hold promise for some types of pancreato-biliary metastases. This review aims to elucidate the current knowledge in this area, which has received sparse attention in the past. The aging population, advances in diagnostic imaging, and improved treatment options may lead to an increase in these rare occurrences going forward.

Value of contrast-enhanced ultrasound combined with percutaneous ultrasound-guided fine-needle aspiration in the diagnosis of solid pancreatic lesions

Background:

Contrast-enhanced ultrasound (CEUS) can detect lesions hidden in inflammatory regions and find necrosis or areas of severe fibrosis within the lesion. This retrospective study aimed to compare the diagnostic accuracy of solid pancreatic lesions using percutaneous ultrasound (US)-guided fine-needle aspiration (FNA) with or without CEUS assessment.

Methods:

Clinical, imaging, and pathologic data of 181 patients from January 2014 to December 2018 in Pecking Union Medical College Hospital, with solid pancreatic masses who underwent percutaneous US-FNA and ThinPrep cytologic test were retrospectively evaluated. Patients were divided into CEUS and US groups according to whether CEUS was performed before the biopsy. According to FNA cytology diagnoses, we combined non-diagnostic, neoplastic, and negative cases into a negative category. The positive category included malignant, suspicious, and atypical cases. The final diagnosis was confirmed by pathology or clinical and radiological follow-up for at least 12 months. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of US-FNA were evaluated between the two groups.

Results:

This study enrolled 107 male and 74 female patients (average age: 60 years). There were 58 cases in the US group and 123 cases in the CEUS group. No statistically significant differences in age, gender, or lesion size were found between the two groups. The diagnostic accuracy of the CEUS group was 95.1% (117/123), which was higher than the 86.2% (50/58) observed in the US group (P = 0.036). The sensitivity, specificity, PPV, and NPV of the CEUS group were increased by 7.5%, 16.7%, 3.4%, and 18.8%, respectively, compared with the US group. However, the differences of the two groups were not statistically significant.

Conclusions:

Compared with the conventional US, the use of CEUS could improve the biopsy accuracy and avoid the need for a repeat biopsy, especially for some complicated FNA cases.

Tumour Evolution and Seed and Soil Mechanism in Pancreatic Metastases of Renal Cell Carcinoma

In metastatic renal cell carcinoma, pancreatic metastases can appear in two clinical manifestations: (a) very rarely as isolated pancreatic metastases and (b) in the context with multi-organ metastatic disease. Both courses are characterised by rare, unusual clinical features. For isolated pancreatic metastases, the literature shows no effect on survival in all 11 publications that examined the effect of singular versus multiple pancreatic metastases; a lack of effect on survival time was also present in all 8 studies on pancreatic metastases size, in 7 of 8 studies on the influence of disease-free interval (DFI), and in 6 of 7 studies on the influence of synchronous versus metachronous metastases. In multi-organ site metastases observations, on the other hand, all five available references showed significantly better results in patients with concurrent pancreatic metastases compared to those without pancreatic metastases, although the total number of affected organs in the pancreatic metastases cohort was larger. Tumour volume-dependent risk factors thus remain surprisingly ineffective in both groups, which contradicts the usual behaviour of solid tumours. The reasons for this unusual behaviour and possible relations to tumour evolution and the hypothesis of an influence of a seed and soil mechanism in the occurrence of pancreatic metastases in metastatic renal cell carcinoma are discussed.

Isolated Pancreatic Metastases of Renal Cell Carcinoma-A Paradigm of a Seed and Soil Mechanism: A Literature Analysis of 1,034 Observations

Previously documented arguments, in favor of the suspected impact of a seed and soil mechanism, in the development and progression of isolated pancreatic metastasis of renal cell carcinomas (isPM) are: (1) uniform and independent from the side of the primary tumor distribution of isPM within the pancreas and, (2) the similar survival rates for singular and multiple isPM. In addition, the present study adds new arguments that further confirm the importance of an seed and soil mechanism in isPM: (1) Within the singular isPM, the size of the metastasis does not affect the overall survival; (2) Within the group of multiple isPMs, the overall survival does not depend on the number of metastases; (3) For synchronous and metachronous isPM, survival rates are also not different, and (4) Within the group of metachronous isPM there is also no correlation between the overall survival and interval until metastases occurs. This unusual ineffectiveness of otherwise known risk factors of solid cancers can be explained plausibly by the hypothesis of a very selective seed and soil mechanism in isPM. It only allows embolized renal carcinoma cells in the pancreas to complete all steps required to grow into clinically manifest metastases. In all other organs, on the other hand, the body is able to eliminate the embolized tumor cells or at least put them into a dormant state for many years. This minimizes the risk of occult micrometastases in distant organs, which could later—after isPM treatment—grow into clinically manifest metastases, so that the prognosis of the isPM is only determined by an adequate therapy of the pancreatic foci, and prognostic factors, such as total tumor burden or interval until the occurrence of the isPM remain ineffective.

Metachronous Pancreatic Metastasis from Rectal Cancer that Masqueraded as a Primary Pancreatic Cancer: A Rare and Difficult-to-Diagnose Metastatic Tumor in the Pancreas

BACKGROUND Pancreatic metastasis from colorectal cancer is rare and can masquerade as primary pancreatic cancer. CASE REPORT A 70-year-old male was diagnosed with advanced rectal cancer with multiple liver metastases. After neoadjuvant chemotherapy, he underwent radical surgery for the primary tumor and hepatectomy for multiple liver metastases. Adjuvant chemotherapies and additional surgeries were subsequently required for recurrences in the liver, lung, and lymph nodes. A diffuse hypovascular nodule in the pancreatic head and a solitary liver metastasis were detected 2.5 years after the initial surgery and he accordingly underwent further chemotherapy. However, the pancreatic tumor progressed, invading the pancreatic duct and biliary tract. Obstructive jaundice finally prompted discontinuation of chemotherapy and he underwent biliary drainage. His diffuse and hypovascular tumor was clinically and radiographically diagnosed as a primary pancreatic cancer. Pancreatic resection for the pancreatic tumor and hepatectomy for the liver metastasis were performed 4.2 years after the initial surgery, achieving radiographic and surgical curative resection. Pathological examination of the surgical specimen resulted in a definitive diagnosis of metachronous pancreatic metastasis from his primary rectal cancer. Despite further chemotherapy, his general condition worsened; however, he remains alive 5.4 years after the initial surgery, with best supportive care. CONCLUSIONS Pancreatic metastasis originating from rectal cancer can masquerade as primary pancreatic cancer clinically and radiologically. Multimodality treatment is mandatory for metastatic colorectal cancer. Aggressive surgeries for pancreatic metastasis should be considered if curative resection appears possible radiographically and/or intraoperatively.