Imaging of benign and malignant cystic pancreatic lesions and a strategy for follow up

An unusual case of retroperitoneal synovial sarcoma with CT, MRI, and F-18 FDG PET/CT findings

Synovial sarcoma, predominantly found in the extremities, rarely occurs in the retroperitoneum. Tumors can often grow to a considerable size before diagnosis, which warrant the critical importance of early detection to minimize morbidity and mortality. While the final diagnosis relies on pathologic examination, imaging plays a crucial role in early detection.

The Hong Kong consensus recommendations on the diagnosis and management of pancreatic cystic lesions

Background

The finding of pancreatic cystic lesions (PCL) on incidental imaging is becoming increasingly common. International studies report a prevalence of 2.2-44.7% depending on the population, imaging modality and indication for imaging, and the prevalence increases with age. Patients with PCL are at risk of developing pancreatic cancer, a disease with a poor prognosis. This publication summarizes recommendations for the diagnosis and management of PCL and post-operative pancreatic exocrine insufficiency (PEI) from a group of local specialists.

Methods

Clinical evidence was consolidated from narrative reviews and consensus statements formulated during two online meetings in March 2022. The expert panel included gastroenterologists, hepatobiliary surgeons, oncologists, radiologists, and endocrinologists.

Results

Patients with PCL require careful investigation and follow-up due to the risk of malignant transformation of these lesions. They should undergo clinical investigation and pancreas-specific imaging to classify lesions and understand the risk profile of the patient. Where indicated, patients should undergo pancreatectomy to excise PCL. Following pancreatectomy, patients are at risk of PEI, leading to gastrointestinal dysfunction and malnutrition. Therefore, such patients should be monitored for symptoms of PEI, and promptly treated with pancreatic enzyme replacement therapy (PERT). Patients with poor response to PERT may require increases in dose, addition of a proton pump inhibitor, and/or further investigation, including tests for pancreatic function. Patients are also at risk of new-onset diabetes mellitus after pancreatectomy; they should be screened and treated with insulin if indicated.

Conclusions

These statements are an accurate summary of our approach to the diagnosis and management of patients with PCL and will be of assistance to clinicians treating these patients in a similar clinical landscape.

Giant Pseudocyst of the Pancreas: A Case Report

Pancreatic cysts are usually asymptomatic over 70% of the time. They can be benign or malignant. Enhanced imaging modalities and increased usage of routine imaging have increased the identification of pancreatic cysts. If symptomatic, abdominal pain or back pain, unexplained weight loss, jaundice, steatorrhea or palpable mass are usually the presenting complaints. Pancreatic cysts are typically assessed by cross-sectional computed tomography (CT) and magnetic resonance imaging (MRI). In this article, we present a case of a 33-year-old female with a recurrent large pancreatic pseudocyst, initially measured 15.8 cm x 14 cm x 14 cm, who was subsequently admitted to our unit and managed successfully. After undergoing diagnostic laparoscopy, exploratory laparotomy, and pancreatic cystogastrostomy, the pseudocyst shrunk to 8 cm x 6 cm over 13 weeks. It is rare to come across a pseudocyst of such large dimensions. Despite its large size, the patient presented with vague abdominal pain as the only chief complaint. The unusual presentation of symptoms and the enormous size of the pseudocyst make this a unique case. Managing giant pancreatic pseudocysts can be complex, as seen in this scenario by the multiple approaches attempted to treat the pseudocyst.

Exploring the Clinical Utility of Pancreatic Cancer Circulating Tumor Cells

Pancreatic ductal adenocarcinoma (PDAC) is the most frequent pancreatic cancer type, characterized by a dismal prognosis due to late diagnosis, frequent metastases, and limited therapeutic response to standard chemotherapy. Circulating tumor cells (CTCs) are a rare subset of tumor cells found in the blood of cancer patients. CTCs has the potential utility for screening, early and definitive diagnosis, prognostic and predictive assessment, and offers the potential for personalized management. However, a gold-standard CTC detection and enrichment method remains elusive, hindering comprehensive comparisons between studies. In this review, we summarize data regarding the utility of CTCs at different stages of PDAC from early to metastatic disease and discuss the molecular profiling and culture of CTCs. The characterization of CTCs brings us closer to defining the specific CTC subpopulation responsible for metastasis with the potential to uncover new therapies and more effective management options for PDAC.

Hereditary and Sporadic Pancreatic Ductal Adenocarcinoma: Current Update on Genetics and Imaging

Pancreatic ductal adenocarcinoma (PDAC) is a genetically heterogeneous, biologically aggressive malignancy with a uniformly poor prognosis. While most pancreatic cancers arise sporadically, a small subset of PDACs develop in patients with hereditary and familial predisposition. Detailed studies of the rare hereditary syndromes have led to identification of specific genetic abnormalities that contribute to malignancy. For example, germline mutations involving BRCA1, BRCA2, PRSS1, and mismatch repair genes predispose patients to PDAC. While patients with Lynch syndrome develop a rare "medullary" variant of adenocarcinoma, intraductal papillary mucinous tumors are observed in patients with McCune-Albright syndrome. It is now well established that PDACs originate via a multistep progression from microscopic and macroscopic precursors due to cumulative genetic abnormalities. Improved knowledge of tumor genetics and oncologic pathways has contributed to a better understanding of tumor biology with attendant implications on diagnosis, management, and prognosis. In this article, the genetic landscape of PDAC and its precursors will be described, the hereditary syndromes that predispose to PDAC will be reviewed, and the current role of imaging in screening and staging assessment, as well as the potential role of molecular tumor-targeted imaging for evaluation of patients with PDAC and its precursors, will be discussed. Keywords: Abdomen/GI, Genetic Defects, Oncology, Pancreas Supplemental material is available for this article. © RSNA, 2020.

Natural history of intraductal papillary mucinous neoplasm and non-neoplastic cyst: long-term imaging follow-up study

BACKGROUND

To identify differences in incidence and mortality of pancreatic cancer (PC) between intraductal papillary mucinous neoplasm (IPMN) and non-neoplastic cyst.

METHODS

Patients with pancreatic cyst (n = 526; 263 with IPMN and 263 with non-neoplastic cyst matched for age, sex, and diagnosis year) were periodically followed-up with imaging. Hazard ratio (HR), standardized incidence ratio (SIR), and standardized mortality ratio (SMR) for PC and PC-related mortality were estimated.

RESULTS

During a mean follow-up of 57.5 months with 3,376 computed tomography scans and 1,079 magnetic resonance imaging scans, 5-year cumulative PC incidence was 4.0% for IPMN and 0% for non-neoplastic cyst, respectively (HR 5.2; P = 0.031). During a mean follow-up of 73.1 months, 5-year cumulative PC-related mortality was 2.6% for IPMN and 0% for non-neoplastic cyst, respectively (HR 4.5; P = 0.05). Compared with the general population in Japan, patients with IPMN, but not those with non-neoplastic cyst, had significantly increased risks of PC incidence (SIR 22.03) and related mortality (SMR 15.9).

CONCLUSIONS

During long-term imaging follow-up, patients with IPMN developed PC over time, whereas none of the patients with non-neoplastic cyst developed it within 5 years. Compared with the general population, patients with IPMN, but not those with non-neoplastic cyst, were at risk of PC and related mortality.

Pancreatic cysts: What imaging characteristics are associated with development of pancreatic ductal adenocarcinoma?

PURPOSE

To assess relationship between pancreatic cysts (PC) and pancreatic ductal adenocarcinoma (PDAC) and to compare imaging features of PC in subjects who develop PDAC and those who do not.

MATERIAL AND METHODS

This case-control IRB-approved HIPAA-compliant study included patients with PDAC (cases) and lung cancer (controls), diagnosed between 1/1/05-1/1/14. The most recent abdominal CT/MR of each patient done >6months prior to cancer diagnosis date was reviewed by radiologist blinded to case/control status. Presence of PC, number and size of largest PC, presence of main pancreatic duct (MPD) dilatation (MPD >3mm) were recorded. Simple PC was defined as lack of calcifications, septations and enhancement. Logistic regression models with binary outcome of PDAC were constructed.

RESULTS

There were 88 cases and 273 controls with mean ages of 69.6 years (±10.3) and 69.8 years (±12.0), respectively (p=0.864). PC were present in 21.6% (19/88) cases and in 9.2% (25/273) controls (p=0.002). The OR of PC for development of PDAC was 2.83, adjusting for age, sex and race (p=0.001). Mean PC size was 14.8mm (±8.7) in cases and 7.6mm (±8.0) in controls (p=0.007). PC were solitary in 6 (31.6%) of 19 cases and 21 (84.0%) of 25 controls (p=0.001). There was no significant difference in proportions of simple cysts or MPD dilatation between cases and controls. Multiple PC had 8.2 times increased odds of PDAC compared with solitary PC, adjusting for cyst size (p=0.007).

CONCLUSION

Multiple PC are associated with 8.2 times higher odds of PDAC compared with solitary PC.

Synovial sarcoma: Magnetic resonance and computed tomography imaging features and differential diagnostic considerations

The present study retrospectively examined 24 cases of pathologically confirmed synovial sarcoma and analyzed the clinical presentation and imaging findings in order to explore the imaging features of synovial sarcoma. The majority of the lesions were large (>5 cm; 88%), rounded or lobulated, relatively well-defined tumor masses in the extremities near the joints or deeply located. On computed tomography (CT) scans, the lesions demonstrated intensity signals similar to those of muscle. Six cases exhibited punctate calcification in the periphery of the tumor. On T1-weighted images, the largest lesions of >5 cm, were usually heterogeneous, with a signal intensity similar to or slightly higher than that of muscle. On T2-weighted images, heterogeneous high-intensity or slightly high-intensity signals were observed, with 12 cases exhibiting a high signal consistent with hemorrhage and 12 presenting signals that indicated internal septations. Contrast-enhanced scanning revealed heterogeneous enhancement in the majority of the lesions and no enhancement in areas of cystic necrosis or internal septations. Synovial sarcoma has specific imaging features, and comprehensive analysis of CT and magnetic resonance imaging can improve the accuracy of the pre-operative diagnosis.

To fine needle aspiration or not? An endosonographer's approach to pancreatic cystic lesions

Endoscopic ultrasound (EUS) guided fine needle aspiration (FNA) is an established diagnostic tool in the management of pancreatic cystic lesions (PCLs). Due to the proximity to the target lesion, the fine diagnostic needle travels through only minimal normal tissues. The risks of bleeding, pancreatitis and infection are small. Valuable diagnostic morphological information can be obtained by EUS before the use of FNA. The additional cytopathologic and cyst fluid analysis for the conventional markers such as amylase, carcinoembryonic antigen (CEA) and CA19.9 improves the diagnostic capability. Pancreatic cyst fluid CEA concentration of 192 ng/mL is generally the most agreed cutoff to differentiate mucinous from non-mucinous lesion. A fluid amylase level of <250 IU/L excludes the diagnosis of pseudocyst. Technical tips of EUS-FNA and the limitations of the procedure are discussed. Promising technique and FNA needle modifications have been described to improve the diagnostic yield at the cytopathologic analysis. The use of novel cyst fluid proteomics and deoxyribonucleic acid-based biomarkers of the PCLs are reviewed. Although it is considered a safe procedure, EUS-FNA is not a routine in every patient. Recommendations of the role of EUS-FNA at various common clinical scenarios are discussed.

Pancreatic cysts: etiology, diagnosis and management

Pancreatic cysts involve a wide spectrum of pathologies from post-inflammatory cysts to malignant neoplasms. Pancreatic pseudocysts, serous cystadenomas, mucinous cystadenomas, intraductal papillary mucinous neoplasms (IPMNs) and solid pseudopapillary tumors occur most frequently. Differential diagnosis involves the following imaging investigations: transabdominal ultrasonography (TUS), contrast enhanced ultrasonography (CEUS) and endoscopic ultrasonography (EUS), computed tomography (CT), magnetic resonance (MR) and magnetic resonance cholangiopancretography (MRCP), endoscopic retrograde cholangiopancretography (ERCP). The cyst fluid cytology is performed in difficult differential diagnosis between pseudocysts and benign and potentially malignant or malignant tumors. Most frequently, viscosity, amylase, CEA and CA 19-9 levels are determined. Imaging findings should be correlated with cytology. The management depends on the cyst type and size. Small asymptomatic pseudocysts, serous cystadenomas and branchduct IPMNs should be carefully observed, whereas symptomatic large or uncertain serous cystadenomas and cystadenocarcinomas, mucinous cystadenomas and cystadenocarcinomas, main-duct IPMNs and large branch-duct IPMNs with malignant features, serous and mucinous cystadenocarcinomas, and solid pseudopapillary tumors require surgery. Pseudocysts are usually drained. Percutaneous / EUS-guided or surgical cyst drainage can be performed. Complicated and uncertain pseudocysts and cystic tumors need surgical resection. The type of surgery depends on cyst location and size and includes proximal, central, distal, total pancreatectomies and enucleation.

Diagnosis and treatment of pancreatic pseudocysts and cystic tumors based on own material and quoted literature

Pseudocysts constitute the most basic cystic lesions of the pancreas. Symptomatic cysts may be treated by means of both minimally invasive methods and surgery. Currently, it is believed that approximately 5% of cystic lesions in the pancreas may in fact, be neoplastic cystic tumors. Their presence is manifested by generally irregular multilocular structures, solid nodules inside the cyst or in the pancreatic duct, frequently vascularized, as well as fragmentary thickening of the cystic wall or septation.

Pancreatic cystic lesions: How endoscopic ultrasound morphology and endoscopic ultrasound fine needle aspiration help unlock the diagnostic puzzle

Cystic lesions of the pancreas are being diagnosed with increasing frequency, covering a vast spectrum from benign to malignant and invasive lesions. Numerous investigations can be done to discriminate between benign and non-evolutive lesions from those that require surgery. At the moment, there is no single test that will allow a correct diagnosis in all cases. Endoscopic ultrasound (EUS) morphology, cyst fluid analysis and cytohistology with EUS-guided fine needle aspiration can aid in this difficult diagnosis.

Cystic tumors of the pancreas: imaging and management

Cystic tumors of the pancreas are a subset of rare pancreatic tumors that vary from benign to malignant. Many have specific imaging findings that allow them to be differentiated from each other. This article (1) reviews the imaging features of the common cystic pancreatic lesions, including serous microcystic adenoma, mucinous cystic tumor, intraductal papillary mucinous tumor, and solid pseudopapillary tumor, and including the less common lesions such as cystic endocrine tumors, cystic metastases, cystic teratomas, and lymphangiomas; and (2) provides comprehensive algorithms on how to manage the individual lesions, with recommendations on when to reimage patients.