MRI features of pancreatic colloid carcinoma

Large Duct Pancreatic Ductal Adenocarcinoma: A Morphological Variant of Pancreatic Ductal Adenocarcinoma With Distinct CT and MRI Characteristics

OBJECTIVE

To investigate the imaging characteristics of large duct pancreatic ductal adenocarcinoma (LD-PDAC) on computed tomography (CT) and magnetic resonance imaging (MRI).

MATERIALS AND METHODS

Thirty-five patients with LD-PDAC (63.2 ± 9.7 years) were retrospectively evaluated. Tumor morphology on CT and MRI (predominantly solid mass vs. solid mass with prominent cysts vs. predominantly cystic mass) was evaluated. Additionally, the visibility, quantity, shape (oval vs. branching vs. irregular), and MRI signal intensity of neoplastic cysts within the LD-PDAC were investigated. The radiological diagnoses rendered for LD-PDAC in radiology reports were reviewed.

RESULTS

LD-PDAC was more commonly observed as a solid mass with prominent cysts (45.7% [16/35] on CT and 37.1% [13/35] on MRI) or a predominantly cystic mass (20.0% [7/35] on CT and 40.0% [14/35] on MRI) and less commonly as a predominantly solid mass on CT (34.3% [12/35]) and MRI (22.9% [8/35]). The tumor morphology on imaging was significantly associated with the size of the cancer gland on histopathological examination (P = 0.020 [CT] and 0.013 [MRI]). Neoplastic cysts were visible in 88.6% (31/35) and 91.4% (32/35) of the LD-PDAC cases on CT and MRI, respectively. The cysts appeared as branching (51.6% [16/35] on CT and 59.4% [19/35] on MRI) or oval shapes (45.2% [14/35] on CT and 31.2% [10/35] on MRI) with fluid-like MRI signal intensity. In the radiology reports, 10 LD-PDAC cases (28.6%) were misinterpreted as diseases other than typical PDAC, particularly intraductal papillary mucinous neoplasms.

CONCLUSION

LD-PDAC frequently appears as a solid mass with prominent cysts or as a predominantly cystic mass on CT and MRI. Radiologists should be familiar with the imaging features of LD-PDAC to avoid misdiagnosis.

Rare Solid Pancreatic Lesions on Cross-Sectional Imaging

Several solid lesions can be found within the pancreas mainly arising from the exocrine and endocrine pancreatic tissue. Among all pancreatic malignancies, the most common subtype is pancreatic ductal adenocarcinoma (PDAC), to a point that pancreatic cancer and PDAC are used interchangeably. But, in addition to PDAC, and to the other most common and well-known solid lesions, either related to benign conditions, such as pancreatitis, or not so benign, such as pancreatic neuroendocrine neoplasms (pNENs), there are solid pancreatic lesions considered rare due to their low incidence. These lesions may originate from a cell line with a differentiation other than exocrine/endocrine, such as from the nerve sheath as for pancreatic schwannoma or from mesenchymal cells as for solitary fibrous tumour. These rare solid pancreatic lesions may show a behaviour that ranges in a benign to highly aggressive malignant spectrum. This review includes cases of an intrapancreatic accessory spleen, pancreatic tuberculosis, solid serous cystadenoma, solid pseudopapillary tumour, pancreatic schwannoma, purely intraductal neuroendocrine tumour, pancreatic fibrous solitary tumour, acinar cell carcinoma, undifferentiated carcinoma with osteoclastic-like giant cells, adenosquamous carcinoma, colloid carcinoma of the pancreas, primary leiomyosarcoma of the pancreas, primary and secondary pancreatic lymphoma and metastases within the pancreas. Therefore, it is important to determine the correct diagnosis to ensure optimal patient management. Because of their rarity, their existence is less well known and, when depicted, in most cases incidentally, the correct diagnosis remains challenging. However, there are some typical imaging features present on cross-sectional imaging modalities that, taken into account with the clinical and biological context, contribute substantially to achieve the correct diagnosis.

Pancreatic Cystic Lesions: Imaging Techniques and Diagnostic Features

The detection of incidental pancreatic cystic lesions has increased over time. It is crucial to separate benign from potentially malignant or malignant lesions to guide management and reduce morbidity and mortality. The key imaging features used to fully characterize cystic lesions are optimally assessed by contrast-enhanced magnetic resonance imaging/magnetic resonance cholangiopancreatography, with pancreas protocol computed tomography offering a complementary role. While some imaging features have high specificity for a particular diagnosis, overlapping imaging features between diagnoses may require further investigation with follow-up diagnostic imaging or tissue sampling.

Pancreatic colloid adenocarcinoma arising from intraductal papillary mucinous neoplasm: Radiologic-pathologic correlation with cinematic rendering

Intraductal papillary mucinous neoplasms (IPMN) of the pancreas have the potential for malignant progression into adenocarcinoma. Colloid or mucinous non-cystic carcinoma of the pancreas is an uncommon variant neoplasm that can arise within an intestinal type IPMN and have a relatively improved prognosis but may mimic the more lethal tubular or ductal adenocarcinoma. Colloid carcinoma is an infiltrating ductal epithelial neoplasm containing primarily extracellular stromal mucin pools and scant amount of centrally floating neoplastic cells. While several reports have evaluated the unique pathologic and immunohistochemical profile of colloid carcinomas, there has been limited radiologic-pathologic correlation in the literature. We report a case of an 83-year-old female who presented for evaluation of slowly progressive abdominal pain and was found to have colloid carcinoma arising from an IPMN. This is one of the first reports to correlate the multimodality radiology including cinematic rendering (CR) and histopathology features associated with this tumor. An enhanced understanding of the correlation between imaging appearance and specific histopathologic findings may aid in the early recognition and treatment of this rare neoplasm. Emphasis is placed on CR as this may help guide surgical management.

Pancreaticoduodenal Groove: Spectrum of Disease and Imaging Features

The pancreaticoduodenal groove (PDG) is a small space between the pancreatic head and duodenum where vital interactions between multiple organs and physiologic processes take place. Muscles, nerves, and hormones perform a coordinated dance, allowing bile and pancreatic enzymes to aid in digestion and absorption of critical nutrition. Given the multitude of organs and cells working together, a variety of benign and malignant entities can arise in or adjacent to this space. Management of lesions in this region is also complex and can involve observation, endoscopic resection, or challenging surgeries such as the Whipple procedure. The radiologist plays an important role in evaluation of abnormalities involving the PDG. While CT is usually the first-line examination for evaluation of this complex region, MRI offers complementary information. Although features of abnormalities involving the PDG can often overlap, understanding the characteristic imaging and pathologic features generally allows categorization of disease entities based on the suspected organ of origin and the presence of ancillary features. The goal of the authors is to provide radiologists with a conceptual approach to entities implicating the PDG to increase the accuracy of diagnosis and assist in appropriate management or presurgical planning. They briefly discuss the anatomy of the PDG, followed by a more in-depth presentation of the features of disease categories. A table summarizing the entities that occur in this region by underlying cause and anatomic location is provided. ^©RSNA, 2022.

Pancreatic Colloid Carcinoma Presenting with Acute Pancreatitis

Pancreatic colloid carcinoma, also known as mucinous non-cystic carcinoma, is a rare subtype of pancreatic cancer accounting for 1-3% of the pancreatic malignant neoplasms. We herein report a woman who initially presented for acute pancreatitis. Computed tomography showed pancreatic swelling due to acute pancreatitis and a 16-mm mass with an enhanced margin in the pancreatic tail. We performed endoscopic ultrasound fine-needle aspiration. The patient was diagnosed with pancreatic colloid carcinoma, and distal pancreatectomy was performed. This case indicates that pancreatic colloid carcinoma should be considered as a differential diagnosis of pancreatic tumor presenting with acute pancreatitis.

Colloid Carcinoma of the Pancreas with a Series of Radiological and Pathological Studies for Diagnosis: A Case Report

Pancreatic colloid carcinoma is an uncommon and unique malignancy possessing a significantly more favorable prognosis than that of ordinary pancreatic ductal adenocarcinoma. Accurate diagnosis of this rare entity is thus important for leading the ensuing optimal treatment. Herein we report a case of colloid carcinoma of the pancreas with a series of imaging findings and pathologic assessments. Being familiar with these radio-pathological features makes early diagnosis possible prior to operation.

Pancreatic intraductal papillary mucinous neoplasm associated colloid carcinoma

Colloid carcinomas are rare pancreatic tumors characterized by the presence of mucin pools with scarce malignant cells. Most of these neoplasms arise from intestinal-type intraductal papillary mucinous neoplasms (IPMNs). We report a case of a 77-year-old male patient who presented with weight loss, asthenia, lumbar pain and diabetes. Imaging studies revealed a mixed-type IPMN with high-risk features and a possible invasive component. The patient underwent surgical resection and the histology confirmed an invasive colloid carcinoma of the pancreas associated with an intestinal-type IPMN. Although invasive ductal and colloid carcinomas may look similar on imaging studies, its distinction is important because the latter have a better prognosis.

Pancreatic Ductal Adenocarcinoma and Its Variants: Pearls and Perils

Pancreatic ductal adenocarcinoma (PDAC), an epithelial neoplasm derived from the pancreatic ductal tree, is the most common histologic type of pancreatic cancer and accounts for 85%-95% of all solid pancreatic tumors. As a highly lethal malignancy, it is the seventh leading cause of cancer death worldwide and is responsible for more than 300 000 deaths per year. PDAC is highly resistant to current therapies, affording patients a 5-year overall survival rate of only 7.2%. It is characterized histologically by its highly desmoplastic stroma embedding tubular and ductlike structures. On images, it typically manifests as a poorly defined hypoenhancing mass, causing ductal obstruction and vascular involvement. Little is known about the other histologic subtypes of PDAC, mainly because of their rarity and lack of specific patterns of disease manifestation. According to the World Health Organization, these variants include adenosquamous carcinoma, colloid carcinoma, hepatoid carcinoma, medullary carcinoma, signet ring cell carcinoma, undifferentiated carcinoma with osteoclast-like giant cells, and undifferentiated carcinoma. Depending on the subtype, they can confer a better or even worse prognosis than that of conventional PDAC. Thus, awareness of the existence and differentiation of these variants on the basis of imaging and histopathologic characteristics is crucial to guide clinical decision making for optimal treatment and patient management.

Invasive Intraductal Papillary Mucinous Neoplasms: CT Features of Colloid Carcinoma Versus Tubular Adenocarcinoma of the Pancreas

OBJECTIVE. The purpose of this study is to compare the CT features of colloid carcinoma and tubular adenocarcinoma of the pancreas arising in association with intraductal papillary mucinous neoplasms (IPMNs). MATERIALS AND METHODS. The preoperative CT images of 85 patients with histopathologically proven IPMNs and associated invasive adenocarcinoma located next to each other were retrospectively reviewed. Twenty-nine patients (34.1%; 19 men and 10 women; mean [± SD] age, 68.0 ± 9.5 years) had invasive colloid carcinoma, and 56 patients (65.9%; 31 men and 25 women; mean age, 70.8 ± 10.6 years) had invasive tubular adenocarcinoma. We compared the following CT features between the two groups: IPMN type, main pancreatic duct (MPD) and common bile duct diameters, diameter and characteristics of the largest cystic lesion for branch duct and mixed-type IPMNs, presence of an extracystic or extraductal solid mass next to the cystic lesion or MPD, morphologic features of the upstream MPD in relation to the cystic lesion or solid mass, and presence of a fistula to the adjacent organs. RESULTS. An MPD size of 9.5 mm or greater, a largest cystic lesion diameter of 28 mm or greater, location in the head or neck, septation, calcification, presence of a mural nodule(s) within a cystic lesion or MPD, and presence of a fistula were all more commonly associated with colloid carcinoma. In contrast, presence of an extracystic or extraductal solid mass and an abrupt change in the caliber of the dilated MPD were associated with tubular adenocarcinoma. The best CT feature for differentiating between the two groups was the morphologic features of the upstream MPD in relation to the cystic lesion or solid mass (sensitivity, 81.3%; specificity, 92.3%). CONCLUSION. Preoperative CT is helpful in differentiating two types of invasive carcinoma arising in association with IPMNs. These findings are clinically important because prognosis is better for colloid carcinoma than for tubular adenocarcinoma.

Rare Solid Tumor of the Exocrine Pancreas: A Pictorial Review

Numerous other solid primary neoplasms may arise from the pancreas besides primary ductal adenocarcinomas and neuroendocrine tumors. Although diagnosis can be difficult because of the very low incidence of these tumors, knowledge of several, typical, epidemiologic, biological, and imaging features can help obtain a correct diagnosis. This pictorial review describes the features of solid rare primary pancreatic neoplasms on computed tomography and magnetic resonance imaging focusing on characteristics that can help radiologists differentiate them from classical forms of ductal pancreatic adenocarcinoma and neuroendocrine tumors. Cystic pancreatic neoplasms are beyond the scope of the current review.

Imaging and clinical features of xanthogranulomatous pancreatitis: an analysis of 10 cases at a single institution

PURPOSE

The purpose of the study was to investigate the imaging and clinical features of xanthogranulomatous pancreatitis (XGP).

METHODS

This retrospective series study included 10 patients with pathology-proven XGP. Two radiologists reviewed the computed tomography (CT) and magnetic resonance imaging (MRI) in consensus to determine the morphological features of XGP. The lesion enhancement pattern on dynamic contrast-enhanced scans and the MR signal intensity were also evaluated. Clinical data including symptoms, underlying pancreatic disease, and laboratory findings were reviewed.

RESULTS

Two XGP cases were of a solid type; six were of cystic type, and two were mixed type. XGP usually showed a lobulated contour (90%) and heterogeneous enhancement (100%), with lesion size varying from 2 to 11 cm. Perilesional infiltration was common (90%), but pancreatic duct dilatation was less frequent (30%). Cystic type XGP mostly had an irregular thick wall (83%). On dynamic contrast-enhanced CT/MRI, XGP enhanced progressively from arterial to portal or delayed phases. Lesions appeared hypointense on T1-weighted images (89%) and hyperintense on T2-weighted images (100%). All lesions appeared hyperintense on diffusion-weighted images, with the majority (78%) showing diffusion restriction on apparent diffusion coefficient maps. The patients often had abdominal pain (80%) and underlying pancreatic disease (80%), but mostly had normal or clinically insignificant laboratory findings.

CONCLUSIONS

XGP typically manifests as a clinically silent lobulated heterogeneous mass, with a progressive enhancement pattern and/or irregular thick wall, and diffusion restriction on CT/MRI. Awareness of the imaging and clinical features of XGP may help differentiate it from pancreatic neoplasms, thereby reducing unnecessary surgery.

Pancreas ductal adenocarcinoma with cystic features on cross-sectional imaging: radiologic-pathologic correlation

Most pancreatic ductal adenocarcinomas (PDAs) show solid growth pattern, but ductal adenocarcinomas may demonstrate intratumoral cystic appearance or accompany peritumoral non-neoplastic cystic lesions, thus mimicking cystic pancreatic tumors on imaging studies. The histopathologic findings for PDA with cystic feature are divided into neoplastic and non-neoplastic cysts. Neoplastic cystic changes include large-duct type cysts (microcystic appearance), neoplastic mucin cysts (macrocystic appearance), colloid carcinomas (mucinous noncystic adenocarcinomas), and degenerative cystic change usually caused by hemorrhagic necrosis of tumor. Non-neoplastic cystic changes include retention cysts caused by ductal obstruction and pseudocysts caused by tumor-associated pancreatitis. Depending on the presence, size, number, and configuration of cystic changes, PDA should be differentiated from various types of cystic neoplasms. This pictorial essay provides histopathologic classification of PDAs with cystic features along with the corresponding cross-sectional imaging findings, and their differential diagnosis.

Assessment of pancreatic colloid carcinoma using 18F-FDG PET/CT compared with MRI and enhanced CT

Pancreatic colloid carcinoma (CC) is a rare sub-type of pancreatic adenocarcinoma which has an improved prognosis compared with pancreatic ductal carcinoma. Consequently, the early detection of CC by imaging may be of great significance in guiding patient management and therapeutic decisions. The present study aimed to analyze ¹⁸F-FDG PET/CT findings of CC in comparison to MRI and CT. PET/CT findings in 5 patients with CC were retrospectively reviewed based on visual interpretation and semi-quantitative index of SUV_max and TNR. Four patients received dual-time-point PET/CT scans. Additionally, one patient underwent contrast-enhanced CT scan, one MRI, and three received both. A total of five lesions were detected in five patients. Visually, two cases presented with mild FDG uptake, two with moderate and one with high. The mean of SUV_max and TNR was 5.1±2.2 and 2.8±0.7, respectively. Compared with CCs with low SUV_max, CCs with high SUV_max were more aggressive. No distant metastases were observed in five cases. Among four patients with dual-time-point PET/CT imaging, SUV_max increased in three cases and decreased in one case. The mean early and delayed SUV_max were 4.2±1.1 and 4.7±1.9, respectively (P>0.05). Radiological findings mainly included septated cystic components, internal sponge-like contrast-enhancement, calcification and 'salt-and-pepper sign' on MRI T2-weighted imaging. Thus, PET/CT provided additional information on metabolic tumor activity as well as locoregional and distant staging, which are important prognostic markers and may improve further patient management. However, PET/CT did not show any findings in addition to MRI and contrast-enhanced CT that were unique to CC and allowed a clear differentiation from other pancreatic malignancies.

Imaging comparison of tubular and colloid pancreatic adenocarcinoma arising from intraductal papillary mucinous neoplasm on multidetector CT

PURPOSE

This study aims to compare tubular pancreatic ductal adenocarcinoma (tPDAC) and colloid subtype pancreatic ductal adenocarcinoma (cPDAC) associated with intraductal papillary mucinous neoplasms (IPMNs) on computed tomography.

METHODS

An institutional review board-approved retrospective study included patients with either IPMN tPDAC or cPDAC. Enhancing mural nodules (MN), solid component (SC), main pancreatic duct (MPD) diameter, and abrupt change in MPD caliber were evaluated.

RESULTS

A total of 22 patients with cPDAC and 17 patients with tPDAC showed no significant difference in MPD size. MN and SC were seen in cPDAC/tPDAC in 55%/18% and 9%/53%, respectively. Abrupt change in MPD caliber was seen in cPDAC/tPDAC at 18%/59%.

CONCLUSION

cPDAC and tPDAC differ in the frequency of MN, SC, and changes in MPD caliber.

Colloid (mucinous non-cystic) carcinoma of the pancreas: A case report

Colloid carcinoma (CC) of the pancreas, also known as mucinous non-cystic carcinoma, is a rare histological variant of pancreatic cancer. The present study reports the case of a 65-year-old male with a pancreatic head tumor 4.6×3.1 cm in size. The tumor had not invaded the superior mesenteric or celiac arteries. Laboratory data showed elevated alkaline phosphatase, γ-gluytamyl transpeptidase and cancer antigen 19-9 (CA19-9) levels. The patient underwent a pancreaticoduodenectomy (PD), and the pathology revealed CC extending to the submucosa of the duodenum, with mild atypical hyperplasia of the pancreatic duct. The patient was negative for circulating tumor cells, indicating a good prognosis. The CA19-9 concentration decreased to within the normal range following surgery. The present study reports a rare case of CC of the pancreas presenting with obstructive jaundice, in which a PD procedure was performed. Primary surgical treatment with curative intent is the optimal management and this subtype of pancreatic cancer is associated with a better prognosis compared with pancreatic ductal adenocarcinoma.

Primary solid pancreatic tumors: recent imaging findings updates with pathology correlation

The imaging findings of primary solid pancreatic tumors have long been studied and are generally well-established. However, interestingly enough, a wealth of new information has recently appeared in the literature, including the imaging findings of novel or previously seldom-addressed pathological entities as well as atypical imaging findings of common tumors, both of which are well-correlated with the pathology findings. 5 %-14 % of pancreatic ductal adenocarcinomas have been reported on dynamic contrast-enhanced computed tomography to be isoattenuating, and thus making the imaging diagnosis challenging. The imaging-pathology correlation in such isoattenuating tumors is presented along with a discussion regarding the early imaging detection of pancreatic cancers. Colloid (or mucinous non-cystic) pancreatic cancer may resemble a less harmful cystic lesion due to its abundant extracellular mucin, and thus requiring caution in the image interpretation. Serotonin-producing neuroendocrine tumors have recently been recognized as a separate entity from usual neuroendocrine tumors. Exuberant fibrosis caused by serotonin metabolites and scarce tumor cells creates a unique pattern of pancreatic ductal obstruction seen on imaging. Small solid pseudopapillary tumors appear as unencapsulated, completely solid lesions with gradually increasing enhancement after contrast administration, unlike typical solid pseudopapillary neoplasms that present as a large mixed solid and degenerated cystic or hemorrhagic mass encapsulated by a thick capsule and which, therefore, tend to be misdiagnosed on imaging. Solid serous adenoma is a rare, solid variant of serous cystadenoma and appears on imaging as a hypervascular, solid nodule due to its genuinely microscopic cystic, alveolar, and ectatic tubular tumor architecture.

Imaging features of the less common pancreatic masses

Contrast-enhanced multiphase CT and dynamic gadolinium-enhanced MR have been validated in the literature as outstanding modalities for the evaluation of pancreatic pathology. In addition to the more frequently seen pancreatic adenocarcinoma, neuroendocrine tumors of the pancreas and cystic lesions such as serous and mucinous cystadenomas and IPMNs, a variety of benign and malignant lesions may occur in the pancreas. The purpose of this pictorial essay is to review the imaging findings of a variety of uncommon, benign and malignant, pancreatic neoplasms.

Contrast-enhanced multiphasic CT and MRI findings of adenosquamous carcinoma of the pancreas

OBJECTIVE

The objective was to retrospectively study computed tomography (CT) and magnetic resonance imaging (MRI) findings of adenosquamous carcinoma of the pancreas (PASC).

MATERIALS AND METHODS

Twelve patients (six women and six men; mean age, 61.3 years; range, 47-78 years) who presented with PASC as documented by pathologic examination underwent CT (n=10) or both CT and MRI (n=2) examination. Two radiologists evaluated the images and determined the location, size, margin, internal attenuation or signal intensity, contrast enhancement, and pattern for each tumor. Additionally, the presence of poorly enhanced areas, upstream main pancreatic duct (MPD) dilatation, pancreatic atrophy, and peripancreatic tissue metastasis were evaluated. Images were cross-referenced to surgical and pathologic findings.

RESULTS

Masses were distributed throughout the pancreas (head, n=6; body, n=1; and tail, n=5). The tumor size ranged from 2.4 to 5.5 cm with an average size of 3.7 cm. Eight (66.7%) masses were ill defined, and seven (58.3%) were partially exophytic. Twelve (100%) masses showed heterogeneous and poorly enhanced areas. The lesions showed weak (n=5), moderate (n=5), or intense (n=2) progressive enhancement. The diameter of MPD in six patients ranged from 3.0 to 5.0 mm with an average of 3.7 mm. Pancreatic atrophy was not found. In 10 patients (83.3%), masses invaded the peripancreatic tissues. Two patients had metastatic liver disease at presentation.

CONCLUSION

PASC typically presented as an ill-defined, hypovascular mass with a poorly enhanced area, exophytic tendency, and peripancreatic tissue invasion. Lack of pancreatic atrophy and mild MPD dilatation were also distinct from common duct pancreatic adenocarcinoma.

Colloid carcinoma of the extrahepatic biliary tract with metastatic lymphadenopathy mimicking cystic neoplasm: a case report

The patient is a previously healthy 52-year-old woman who presented with dyspepsia for two months. Multiple imaging modalities including ultrasound, computed tomography (CT), and magnetic resonance imaging (MRI) showed diffuse bile duct dilatation with an obstructive lesion of the distal extrahepatic biliary duct (EHD) as well as two masses in the peripancreatic area. The peripancreatic masses appeared cystic with posterior acoustic enhancement on ultrasound, low density on CT imaging, and high signal intensity on T2-weighted MRI. The lesion in the distal EHD exhibited similar characteristics on CT and MRI. A Whipple procedure was performed and histological specimens showed malignant cells with large mucin pools that was consistent with a diagnosis of colloid carcinoma of the EHD with metastatic lymphadenopathies. Colloid carcinoma, also called mucinous carcinoma, is classified as a histologic variant of adenocarcinoma. Because the colloid carcinoma of the biliary tree is exceedingly rare, the imaging characteristics and the clinical features of colloid carcinoma remain relatively unknown. We report a case of colloid carcinoma of the common bile duct and its accompanied metastatic lymphadenopathies with characteristic imaging findings reflecting abundant intratumoral mucin pools.