(18)F-FDG-PET/CT findings in pancreatic metastasis

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.

Metastatic pancreatic cancer: Mechanisms and detection (Review)

Pancreatic cancer (PC) is a lethal malignancy. Its prevalence rate remains low but continues to grow each year. Among all stages of PC, metastatic PC is defined as late-stage (stage IV) PC and has an even higher fatality rate. Patients with PC do not have any specific clinical manifestations. Most cases are inoperable at the time-point of diagnosis. Prognosis is also poor even with curative-intent surgery. Complications during surgery, postoperative pancreatic fistula and recurrence with metastatic foci make the management of metastatic PC difficult. While extensive efforts were made to improve survival outcomes, further elucidation of the molecular mechanisms of metastasis poses a formidable challenge. The present review provided an overview of the mechanisms of metastatic PC, summarizing currently known signaling pathways (e.g. epithelial-mesenchymal transition, NF-κB and KRAS), imaging that may be utilized for early detection and biomarkers (e.g. carbohydrate antigen 19-9, prostate cancer-associated transcript-1, F-box/LRR-repeat protein 7 and tumor stroma), giving insight into promising therapeutic targets.

Pancreatic FDG uptake on follow-up PET/CT in patients with cancer

To evaluate the breakdown of unexpected pancreatic ¹⁸F-fluorodeoxyglucose (FDG) uptake and the proportion of secondary primary pancreatic cancer on follow-up, patients with cancer underwent positron emission tomography/computed tomography (PET/CT). The participants consisted of 4,473 consecutive patients with cancer who underwent follow-up PET/CT between January 2015 and March 2019 at Kochi Medical School. Among the participants, 225 with a history of pancreatic cancer were excluded from the present study. Retrospective and blinded PET/CT evaluations of 4,248 patients were performed. In patients with pancreatic FDG uptake, the distribution of FDG uptake in the pancreas was evaluated. The final diagnosis was determined pathologically. A total of 14 (0.3%) of the 4,248 patients exhibited FDG uptake in the pancreatic area. Pancreatic abnormalities were detected in 14 patients, and included five cases of pancreatic metastases (36%), four cases of secondary primary pancreatic cancer (29%), two cases of lymph node metastases (14%), one case of malignant lymphoma (7%), one case of autoimmune pancreatitis (7%) and one case of pseudolesion (7%). One patient with early-stage secondary primary pancreatic cancer had a maximum standardized uptake value (SUV_max) <3.0. The remaining 13 patients had a SUV_max >3.0 in the pancreas. Of the 14 patients, two had multiple foci of FDG uptake in the pancreas. Patients with multiple foci of FDG uptake exhibited pancreatic metastasis from renal cell carcinoma and malignant lymphoma. In conclusion, the majority of patients with unexpected pancreatic FDG uptake on follow-up PET/CT exhibited malignancies; furthermore, ~30% of the malignancies detected in patients with pancreatic FDG uptake were secondary primary pancreatic cancers. In patients with unexpected pancreatic FDG uptake on follow-up PET/CT, primary cancer should be considered as well as metastatic tumors.

Isolated Pancreatic Metastasis From Squamous Cell Lung Cancer Mimicking Primary Pancreatic Ductal Adenocarcinoma on FDG PET/CT

Isolated pancreatic metastasis from lung cancer is rare. We present a case of isolated pancreatic metastasis from squamous cell lung cancer. The pancreatic tumor showed hypovascularity on enhanced MRI and intense FDG uptake on FDG PET/CT mimicking primary pancreatic ductal adenocarcinoma. This case indicates pancreatic metastasis should be considered as a differential diagnosis in patients with a history of extrapancreatic cancer and hypermetabolic pancreatic lesion.

Concurrent Pancreatic Metastasis From Lung Adenocarcinoma and Primary Cholangiocarcinoma on FDG PET/CT Imaging

A 67-year-old man with a history of left upper lobe resection of poorly differentiated adenocarcinoma 1 year ago underwent FDG PET/CT for restaging. The images demonstrated a round cystic lesion with peripheral FDG uptake and centrally photopenic region. Additional focus of increased activity was detected in the left lobe of the liver. The patient underwent the Whipple and partial hepatectomy. The surgical pathology demonstrated concurrently the metastasis to the pancreas from the lung adenocarcinoma and a primary moderately differentiated cholangiocarcinoma.

Laparoscopic pancreaticoduodenectomy for metastatic pancreatic melanoma: A case report

RATIONALE

Pancreatic metastases from other malignant tumors are an uncommon clinical condition and account for approximately 2% of all pancreatic malignancies. The most common primary malignancy that metastasizes to pancreas is renal cell cancer. We reported a rare clinical case of metastatic melanoma to pancreas who underwent a successful laparoscopic pancreaticoduodenectomy (LPD) at our department.

PATIENT CONCERNS

A 54-year-old Chinese man complaining an unexplained jaundice was found to have a pancreatic mass and he was diagnosed with cutaneous melanoma (CM) 6 years ago.

DIAGNOSES

Contrast-enhanced computed tomography (CECT) revealed a solid hypovascular mass measuring about 3.1 × 2.4 cm localized at the junction of pancreatic head and uncinate process, which compressed the lower common bile duct resulting in expansion of the upstream bile ducts.

INTERVENTIONS

We performed an LPD and regional lymphadenectomy on this patient.

OUTCOMES

This patient was discharged home on postoperative day 19. Postoperative pathological results revealed a malignant melanoma with negative margins. Immunohistochemical (IHC) findings also suggested a malignant pancreatic tumor accompanied by necrosis and pigmentation, which confirmed the pathological diagnosis. Immunoreactivity was strongly positive for anti-S-100 protein (+++) and positive for anti-Vimentin (+). The cancer cells were negative for CEA, CK8/18, P53, Violin, CK19, SMA with Ki-67 over 40%. So this pancreatic mass was proved to be a metastatic pancreatic melanoma from the primary cutaneous lesion. After LPD, this patient was followed up by readmission to hospital every 2 month in the first half year. The serum bilirubin and tumor markers such as CA199 were normal. CECT and did not find any newly developed neoplasm at the pancreas or metastasis at other organs. At the last follow-up at 6 months after LPD, the patient's general condition was acceptable and the physical examination and imaging studies revealed no significant findings of melanoma.

LESSONS

Metastatic pancreatic tumors are often associated with well-defined margins, tumor necrosis, enhancement, and distant metastases without pancreatic duct dilatation and parenchymal atrophy. As the most common type of metastatic pancreatic tumor, renal cell cancers tend to have higher attenuation values than that of primary pancreatic cancer, while they had similar attenuation values on the portal phase. Primary pancreatic cancer was always associated with an elevated CA199, total bilirubin, and fasting plasma glucose levels. Surgical resection for metastases to pancreas should be aggressively considered in selected patients due to its unique value of providing palliation and a chance to cure. For patients with unresectable lesions, new therapeutic protocols should be recommended such as the combination of BRAF with MEK inhibitor and PD-1 blocker with or without ipilimumab.

Diagnostic accuracy of different imaging modalities following computed tomography (CT) scanning for assessing the resectability with curative intent in pancreatic and periampullary cancer

BACKGROUND

Periampullary cancer includes cancer of the head and neck of the pancreas, cancer of the distal end of the bile duct, cancer of the ampulla of Vater, and cancer of the second part of the duodenum. Surgical resection is the only established potentially curative treatment for pancreatic and periampullary cancer. A considerable proportion of patients undergo unnecessary laparotomy because of underestimation of the extent of the cancer on computed tomography (CT) scanning. Other imaging methods such as magnetic resonance imaging (MRI), positron emission tomography (PET), PET-CT, and endoscopic ultrasound (EUS) have been used to detect local invasion or distant metastases not visualised on CT scanning which could prevent unnecessary laparotomy. No systematic review or meta-analysis has examined the role of different imaging modalities in assessing the resectability with curative intent in patients with pancreatic and periampullary cancer.

OBJECTIVES

To determine the diagnostic accuracy of MRI, PET scan, and EUS performed as an add-on test or PET-CT as a replacement test to CT scanning in detecting curative resectability in pancreatic and periampullary cancer.

SEARCH METHODS

We searched MEDLINE, Embase, Science Citation Index Expanded, and Health Technology Assessment (HTA) databases up to 5 November 2015. Two review authors independently screened the references and selected the studies for inclusion. We also searched for articles related to the included studies by performing the "related search" function in MEDLINE (OvidSP) and Embase (OvidSP) and a "citing reference" search (by searching the articles that cite the included articles).

SELECTION CRITERIA

We included diagnostic accuracy studies of MRI, PET scan, PET-CT, and EUS in patients with potentially resectable pancreatic and periampullary cancer on CT scan. We accepted any criteria of resectability used in the studies. We included studies irrespective of language, publication status, or study design (prospective or retrospective). We excluded case-control studies.

DATA COLLECTION AND ANALYSIS

Two review authors independently performed data extraction and quality assessment using the QUADAS-2 (quality assessment of diagnostic accuracy studies - 2) tool. Although we planned to use bivariate methods for analysis of sensitivities and specificities, we were able to fit only the univariate fixed-effect models for both sensitivity and specificity because of the paucity of data. We calculated the probability of unresectability in patients who had a positive index test (post-test probability of unresectability in people with a positive test result) and in those with negative index test (post-test probability of unresectability in people with a positive test result) using the mean probability of unresectability (pre-test probability) from the included studies and the positive and negative likelihood ratios derived from the model. The difference between the pre-test and post-test probabilities gave the overall added value of the index test compared to the standard practice of CT scan staging alone.

MAIN RESULTS

Only two studies (34 participants) met the inclusion criteria of this systematic review. Both studies evaluated the diagnostic test accuracy of EUS in assessing the resectability with curative intent in pancreatic cancers. There was low concerns about applicability for most domains in both studies. The overall risk of bias was low in one study and unclear or high in the second study. The mean probability of unresectable disease after CT scan across studies was 60.5% (that is 61 out of 100 patients who had resectable cancer after CT scan had unresectable disease on laparotomy). The summary estimate of sensitivity of EUS for unresectability was 0.87 (95% confidence interval (CI) 0.54 to 0.97) and the summary estimate of specificity for unresectability was 0.80 (95% CI 0.40 to 0.96). The positive likelihood ratio and negative likelihood ratio were 4.3 (95% CI 1.0 to 18.6) and 0.2 (95% CI 0.0 to 0.8) respectively. At the mean pre-test probability of 60.5%, the post-test probability of unresectable disease for people with a positive EUS (EUS indicating unresectability) was 86.9% (95% CI 60.9% to 96.6%) and the post-test probability of unresectable disease for people with a negative EUS (EUS indicating resectability) was 20.0% (5.1% to 53.7%). This means that 13% of people (95% CI 3% to 39%) with positive EUS have potentially resectable cancer and 20% (5% to 53%) of people with negative EUS have unresectable cancer.

AUTHORS' CONCLUSIONS

Based on two small studies, there is significant uncertainty in the utility of EUS in people with pancreatic cancer found to have resectable disease on CT scan. No studies have assessed the utility of EUS in people with periampullary cancer.There is no evidence to suggest that it should be performed routinely in people with pancreatic cancer or periampullary cancer found to have resectable disease on CT scan.