Uncommon solid pancreatic neoplasms: ultrasound, computed tomography, and magnetic resonance imaging features

IgG4-related inflammatory pancreatic head pseudotumor mirrors pancreatic head tumor: A novel case series with a review of the literature

Key Clinical Message

In this noteworthy case series regarding pancreatic pseudo tumors, we intend to spread knowledge among physicians for the diagnostic and therapeutic approach and eventual disease prognosis.

Abstract

Inflammatory pseudotumor of pancreatic head greatly mimics pancreatic head tumor. One of them is IgG4-related pancreatic disease, which is commonly mistaken as neoplastic disease on imaging. In our novel case series, we report three cases of IgG4-related pancreatic head pseudotumor with patients ranging from 35 to 72 years of age. Patients presented with jaundice and abdominal pain. Alongside initial laboratory workup, abdominal CTs and serum IgG4 levels were also obtained. Imaging features in conjunction with IgG4 levels confirmed the diagnosis of IgG4-related autoimmune pancreatitis. Pancreatic pseudotumors are notorious for being often reported as real tumors. Through our noteworthy case series, we intend to highlight the imaging features and laboratory markers that are crucial in such cases to avoid invasive procedures.

Pancreatic metastasis of leiomyoma found 27 years after uterine fibroid surgery

A 59-year-old female was referred to our hospital for pancreatic tumor. She had undergone resection of uterine fibroids 27 years ago, and leiomyoma in the left thigh 8 years ago. Tumor markers were normal. A well-defined hypoechoic tumor measuring 26 mm × 22 mm was detected at the pancreatic tail using ultrasound. Inside the tumor, a small cystic structure was observed. High-sensitivity Doppler imaging revealed faint signals indicating blood flow from the periphery to the interior. Contrast-enhanced ultrasonography in the arterial phase revealed slow, heterogenous enhancement from the periphery to the center of the mass that occurred later than that in the pancreatic parenchyma. The tumor then exhibited homogeneous enhancement except for the periphery, with subsequent washout. Endoscopic ultrasound-fine-needle aspiration was performed. Histopathological examination diagnosed a leiomyoma. The left thigh tumor resected 8 years ago had been diagnosed as benign metastatic leiomyoma (BML). We considered that the current pancreatic tumor was also BML clinically. We report this case because pancreatic metastasis from uterine fibroids is extremely rare. Uterine fibroids are benign tumors, but there are rare cases of metastasis to various organs, which should be considered when performing ultrasound.

Cytopathology of solid pancreatic neoplasms: An algorithmic approach to diagnosis

The classification and management of solid pancreatic neoplasms has expanded significantly in recent years because of advances in immunohistochemical markers, molecular diagnostics, and therapeutics. Solid pancreatic masses are subdivided into 1) ill-defined, scirrhous, and stroma-rich (ductal adenocarcinoma) and 2) well circumscribed, cellular, and stroma-poor (including neuroendocrine neoplasms, acinar cell carcinoma, pancreatoblastoma, and solid-pseudopapillary neoplasm). Definitive diagnosis, particularly of stroma-poor, circumscribed tumors, requires the incorporation of radiologic and cytologic findings, along with the judicious use of (broad, but limited) immunohistochemical panels (pancytokeratin and neuroendocrine [synaptophysin], acinar [trypsin], and solid-pseudopapillary neoplasm [β-catenin] markers), along with unstained slides. Depending on the initial results, immunohistochemical panels should be expanded to include more confirmatory (acinar and neuroendocrine) markers. This ensures that adequate material is available for definitive diagnosis/subclassification and, in some cases, grading, and/or molecular studies, particularly of grade 3 neuroendocrine neoplasms and mixed-lineage tumors. The objective of this review is to expand the understanding of the cytomorphology of solid pancreatic neoplasms using an integrated, multidisciplinary approach in their diagnosis. Knowledge and understanding of recent updates in the classification of solid pancreatic neoplasms ensures that cytopathologists appropriately triage specimens, judiciously use and interpret ancillary studies, and incorporate these results in reporting.

Primary extra-pancreatic pancreatic-type acinar cell carcinoma in the right perinephric space: A case report and review of literature

BACKGROUND

Primary extra-pancreatic pancreatic-type acinar cell carcinoma (ACC) is a rare malignancy, and has only been reported in the gastrointestinal tract, liver, and lymph nodes until now. Extra-pancreatic pancreatic-type ACC in the perinephric space has not been reported. Herein, we report the first case of ACC in the perinephric space and describe its clinical and imaging features, which should be considered when differentiating perinephric space neoplasms.

CASE SUMMARY

A 48-year-old man with a 5-year history of hypertension was incidentally found to have an asymptomatic right retroperitoneal mass during a routine health check-up. Laboratory tests were normal. Abdominal computed tomography and magnetic resonance imaging showed an oval hypervascular mass with a central scar and enhanced capsule in the right perinephric space. After surgical resection of the neoplasm, the diagnosis was primary extra-pancreatic pancreatic-type ACC. The patient was alive without recurrence or metastasis during a 15-mo follow-up.

CONCLUSION

This is the first report of an extra-pancreatic ACC in right perinephric space, which should be considered as a possible diagnosis in perinephric tumors.

Computed tomography features of acinar cell carcinoma of the pancreas

PURPOSE

To report the computed tomography (CT) features of pancreatic acinar cell carcinoma (ACC) and identify CT features that may help discriminate between pancreatic ACC and pancreatic ductal adenocarcinoma (PDA).

MATERIALS AND METHODS

The CT examinations of 20 patients (13 men, 7 women; mean age, 66.5±10.7 [SD] years; range: 51-88 years) with 20 histopathologically proven pancreatic ACC were reviewed. CT images were analyzed qualitatively and quantitatively and compared to those obtained in 20 patients with PDA. Comparisons were performed using univariate analysis with a conditional logistic regression model.

RESULTS

Pancreatic ACC presented as an enhancing (20/20; 100%), oval (15/20; 75%), well-delineated (14/20; 70%) and purely solid (13/20; 65%) pancreatic mass with a mean diameter of 52.6±28.0 (SD) mm (range: 24-120mm) in association with visible lymph nodes (14/20; 70%). At univariate analysis, well-defined margins (Odds ratio [OR], 7.00; P=0.005), nondilated bile ducts (OR, 9.00; P=0.007), visible lymph nodes (OR, 4.33; P=0.028) and adjacent organ involvement (OR, 5.67; P=0.02) were the most discriminating CT features to differentiate pancreatic ACC from PDA. When present, lymph nodes were larger in patients with pancreatic ACC (14±4.8 [SD]; range: 7-25mm) than in those with PDA (8.8±4.1 [SD]; range: 5-15mm) (P=0.039).

CONCLUSION

On CT, pancreatic ACC presents as an enhancing, predominantly oval and purely solid pancreatic mass that most frequently present with no bile duct dilatation, no visible lymph nodes, no adjacent organ involvement and larger visible lymph nodes compared to PDA.

MR imaging features of pancreatic acinar cell carcinoma

PURPOSE

This study aimed to report the magnetic resonance imaging (MRI) features of acinar cell carcinoma (ACC) of the pancreas including diffusion-weighted MRI findings.

MATERIALS AND METHODS

The MRI examinations of five patients (3 men, 2 women; median age, 61years) with histopathologically proven ACC of the pancreas were retrospectively reviewed. MR images were analyzed qualitatively (location, shape, homogeneity, signal intensity, vascular involvement and extrapancreatic extent of ACC) and quantitatively (tumor size, apparent diffusion coefficient [ADC] and normalized ADC of ACC).

RESULTS

All ACC were visible on MRI, presenting as an oval pancreatic mass (5/5; 100%), with moderate and heterogeneous enhancement (5/5; 100%), with a median transverse diameter of 43mm (Q₁, 35; Q₃, 82mm; range: 30-91mm). Tumor capsule was visible in 4/5 ACC (80%) and Wirsung duct enlargement in 2/5 ACC (40%). On diffusion-weighted MRI, all ACC (5/5; 100%) were hyperintense on the 3 b value images. Median ADC value of ACC was 1.061×10^-3mm²/s (Q₁, 0.870×10^-3mm²/s; Q₃, 1.138×10^-3mm²/s; range: 0.834-1.195×10^-3mm²/s). Median normalized ADC ratio of ACC was 1.127 (Q₁, 1.071; Q₃, 1.237; range: 1.054-1.244).

CONCLUSIONS

On MRI, ACC of the pancreas presents as a large, oval pancreatic mass with moderate and heterogeneous enhancement after intravenous administration of a gadolinium chelate, with restricted diffusion and a median ADC value of 1.061×10^-3mm²/s on diffusion-weighted MRI. Further studies however are needed to confirm our findings obtained in a limited number of patients.

Rare pancreatic tumors

In this review, we will focus on rare pancreatic tumors. Most of these tumors do not have distinct characteristic appearances so the key to diagnosis requires a combination of imaging appearance, laboratory data, patient demographics, and associated medical syndromes in order to narrow the differential diagnosis. Nonetheless, imaging plays a vital role in narrowing the differential and guiding management. While there are many variant pathologic entities that cannot be encompassed by a single review, we aim to illustrate the imaging appearance of less common pancreatic tumors highlighting key distinctive diagnostic characteristics and discuss the implications for management. While there is overlap in the imaging appearances of many of these entities, for educational purposes, lesions will be categorized into solid (hypoenhancing and hyperenhancing), cystic lesions, mesenchymal neoplasms, and neoplasms seen in younger patients (< 40 years).

Uncommon Solid Pancreatic Neoplasm: The Role of New Modalities of Ultrasound Endoscopy

Undifferentiated carcinoma with osteoclast-like cells is a rare pancreatic neoplasm with unique ultrasound endoscopic features. A 59-year-old female presented with a 3-month history of weight loss. Abdominal computed tomography and endoscopic ultrasound showed a large pancreatic tumor with a heterogeneous echotexture and liver metastasis. Endoscopic ultrasound fine needle aspiration was used to establish the diagnosis. In this case report, we review the endoscopic, clinical, and pathological features of this type of tumor and describe for the first time the endoscopic features of real-time elastography and contrast enhancement. Real-time elastography revealed a heterogeneous predominantly blue pattern suggestive of pancreatic malignancy, and the contrast-enhanced endosonography showed a hypervascular mass and distinctive vascular (solid) and avascular (liquid/necrotic) components of the lesion, guiding the fine needle aspiration.

Primary pancreatic plasmacytoma: a rare case report

BACKGROUND

Extramedullary plasmacytoma is a very rare tumor derived from plasma cells and found outside the bone marrow. Most have been identified in patients with the more aggressive anaplastic form of the disease. Only a few cases of primary pancreatic plasmacytoma have been reported.

CASE PRESENTATION

We present a case of a 56-year-old man in whom a pancreatic mass was found incidentally. The lesion was determined to be a pancreatic plasmacytoma after distal pancreatectomy. There are no indications of clinical, laboratory or imaging findings of multiple myeloma nor any association with plasmacytoma in any other places, so the diagnosis of primary pancreatic plasmacytoma was made.

CONCLUSION

Primary pancreatic plasmacytoma is rare and the diagnosis is difficult before surgery.

Acinar cell carcinoma of the pancreas presenting as diffuse pancreatic enlargement: Two case reports and literature review

RATIONALE

Pancreatic acinar cell carcinoma (ACC) is a rare malignant tumor of exocrine pancreas. It is typically a well-marginated large solid mass arising in a certain aspect of the pancreas. Diffuse involvement of ACC in the pancreas is very rare, and may simulate pancreatitis in radiological findings. We report 2 cases of ACC presenting as diffuse enlargement of the pancreas due to tumor involvement without formation of a distinct mass.

PATIENT CONCERNS

The patients consisted of a 41-year-old man with weight loss and a 77-year-old man who was asymptomatic.

DIAGNOSES

Computed tomography (CT) and 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT showed diffuse enlargement of the pancreas forming a sausage-like shape with homogenously increased FDG activity.

INTERVENTIONS

Endoscopic ultrasound (EUS)-guided fine needle aspiration (FNA) biopsy of the pancreatic lesion was performed.

OUTCOMES

Histopathology results from the pancreas confirmed the diagnosis of pancreatic ACC.

LESSONS

Because diffuse enlargement of the pancreas is a common imaging feature of pancreatitis, recognition of this rare morphologic pattern of ACC is important for radiological diagnosis of this tumor.

Magnetic resonance imaging features of uterine sarcoma and mimickers

Uterine myometrial tumors are predominantly benign conditions that affect one-third of women and represent the main indication for hysterectomy. Preoperative imaging is of utmost importance for characterization and for precise mapping of myometrial tumors to best guide therapeutic strategy. New minimally invasive therapeutic strategies including morcellation, myolysis, uterine artery embolization and image-guided radiofrequency or focused ultrasound ablation have been developed for the treatment of uterine leiomyoma. However, preoperative differentiation between atypical leiomyomas and leiomyosarcomas is critical on imaging as uterine sarcoma requires a specific surgical technique to prevent dissemination. A single, rapidly growing uterine tumor, associated with endometrial thickening and ascites, in post-menopausal women is suspicious of uterine endometrial stromal sarcoma and carcinosarcoma. Suggestive magnetic resonance imaging features have been described, but overlap in imaging appearance between uterine leiomyosarcomas and cellular leiomyomas makes it challenging to ascertain the diagnosis. This review aims to illustrate the imaging features of uterine sarcomas and potential mimickers to make the reader more familiar with this serious condition which needs special consideration.

Heterogeneous drug target expression as possible basis for different clinical and radiological response to the treatment of primary and metastatic renal cell carcinoma: suggestions from bench to bedside

Metastatic disease occurs in a significant percentage of patients with renal cell carcinoma (RCC) and is usually associated with an overall poor prognosis. However, not all of the sites of metastases seem to have the same prognostic significance in patients receiving targeted agents. Indeed, patients with lung-only metastases seem to present a better survival than patients with other sites, whereas liver and bone metastases are associated with a worst prognosis. Some clinical studies suggest that metastatic sites are more responsive than primary tumors. This event may be due to intratumor heterogeneity in terms of somatic mutations, chromosome aberrations, and tumor gene expression, primarily centered around Von Hippel-Lindau (VHL) pathway, such as VHL mutations, HIF levels, vascular endothelial growth factor (VEGF) isoforms, and VEGF receptor levels. Nevertheless, these data do not completely explain the discordant biological behavior between primary tumor and metastatic sites. Understanding the causes of this discordance will have profound consequences on translational research and clinical trials in RCC. In this review, we overview current data on the differences between primary RCC and metastases in terms of drug target expression and clinical/radiological response to targeted agents, thus describing the prognostic role of different metastatic sites in RCC patients.

Surgical resection does not improve survival in patients with renal metastases to the pancreas in the era of tyrosine kinase inhibitors

BACKGROUND

The aim of this study was to compare survival of resected and unresected patients in a large cohort of patients with metastases to the pancreas from renal cell carcinoma (PM-RCC).

METHODS

Data from 16 Italian centers involved in the treatment of metastatic RCC were retrospectively collected. The Kaplan-Meier and log-rank test methods were used to evaluate overall survival (OS). Clinical variables considered were sex, age, concomitant metastasis to other sites, surgical resection of PM-RCC, and time to PM-RCC occurrence.

RESULTS

Overall, 103 consecutive patients with radically resected primary tumors were enrolled in the analysis. PM-RCCs were synchronous in only three patients (3 %). In 56 patients (54 %), the pancreas was the only metastatic site, whereas in the other 47 patients, lung (57 %), lymph nodes (28 %), and liver (21 %) were the most common concomitant metastatic sites. Median time for PM-RCC occurrence was 9.6 years (range 0-24 years) after nephrectomy. Surgical resection of PM-RCC was performed in 44 patients (median OS 103 months), while 59 patients were treated with tyrosine kinase inhibitors (TKIs; median OS 86 months) (p = 0.201). At multivariate analysis, Memorial Sloan Kettering Cancer Center risk group was the only independent prognostic factor. None of the other clinical variables, such as age, sex, pancreatic surgery, or the presence of concomitant metastases, were significantly associated with outcome in PM-RCC patients.

CONCLUSIONS

The presence of PM-RCC is associated with a long survival, and surgical resection does not improve survival in comparison with TKI therapy. However, surgical resection leads to a percentage of disease-free PM-RCC patients.

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.

Acinar cell carcinoma of the pancreas: clinical and cytomorphologic characteristics

Acinar cell carcinoma is a rare malignant epithelial neoplasm with predominantly exocrine acinar differentiation and is seen primarily in older men (mean age, 62 years). The presenting symptoms are usually non-specific, and jaundice is often not present. Symptoms relating to the overproduction and release of lipase into the circulation are present in 10-15% of patients. Characteristic cytomorphologic features include a population of cells with minimal pleomorphism, eccentrically placed nuclei with a single prominent nucleoli and moderate hyperchromasia. The cytoplasm is finely granular, and the background may contain granular debris secondary to cytolysis. A significant proportion of the cases also have a minor neuroendocrine component or scattered neuroendocrine cells. Approximately 50% of patients have metastatic disease at presentation, often restricted to the regional lymph nodes and liver. The prognosis is poor, only slightly better than that of pancreatic ductal adenocarcinoma.

Pancreatic GIST with pancreas divisum: A new entity

INTRODUCTION

Gastrointestinal stromal tumours (GISTs) are uncommon intra-abdominal tumours. These tumours tend to arise with a higher frequency in the stomach and the small bowel. In fewer than 5% of cases, they originate primarily from extra-gastrointestinal tumours (EGISTs). Gastrointestinal stromal tumour of the pancreas is very rare. Only few cases have been published. We report the first case of stromal tumour of the pancreas with concomitant pancreas divisum.

PRESENTATION OF CASE

A 39-year-old male who presented with constipation and abdominal pain. A computerized tomography demonstrated a 9cm pancreatic mass, without liver lesions. A Whipple procedure with segmental colectomy was performed with success. After 24months follow up, the patient is doing well and disease-free.

DISCUSSION

Mesenchymal tumours of the pancreas are extremely rare, accounting for less than 1% of all pancreatic tumours. The endoscopic ultrasound is helpful for diagnosis. Surgical resection with negative pathologic margins remains the treatment of choice.

CONCLUSION

in our knowledge, this is the first case of pancreatic GIST with pancreas divisum. Although pancreatic GISTs are uncommon tumours, they must be considered in the differential diagnosis of solid pancreatic lesions. Even though the tumour can be evaluated as high risk, treatment must be aggressive in order to improve survival rate.

Multidetector computed tomography in the study of pancreatic metastases

PURPOSE

The aim of this study was to explore the diagnostic performance of multidetector computed tomography (MDCT) in characterising pancreatic metastases.

MATERIALS AND METHODS

CT examinations of 17 patients affected by pancreatic metastases were retrospectively reviewed. The primary malignancy was renal cell carcinoma (RCC) in eight cases, uterine leiomyosarcoma in two, lung carcinoma in four and breast carcinoma in three. CT images were assessed for lesion number, size and morphology.

RESULTS

Pancreatic lesions were solitary in seven cases and multiple in ten. Lesion size ranged between 8 and 40 mm. Metastases from RCC were hyperattenuating in the arterial phase, metastases from breast cancer and lung cancer were hypoattenuating and metastases from uterine leiomyosarcoma were inhomogeneous. Precise lesion characterisation was obtained by using CT examination in 12 cases. In the remaining five patients, all with solitary metastases from RCC, a precise diagnosis was not possible because the lesions could not be differentiated from a neuroendocrine tumour.

CONCLUSIONS

MDCT allowed pancreatic metastases characterisation in 70.5% of cases. The lesions were the manifestation of widely disseminated neoplastic disease, with the exception of metastases from RCC, which were exclusively located in the pancreas.

Metastatic acinar cell carcinoma of the liver from a benign-appearing pancreatic lesion: a mimic of hepatocellular carcinoma

Acinar cell carcinoma (ACC) is a rare pancreatic tumour with a favourable prognosis compared with the more common ductal adenocarcinoma. The radiological findings of this tumour have been described in the literature; however, only limited data are available regarding the metastatic features of ACC of the liver, the most common metastatic site. We report a case of ACC of the pancreas with a hepatic metastasis from a benign-appearing malignant pancreatic lesion.

CT and MRI features of acinar cell carcinoma of the pancreas with pathological correlations

AIM

To document the computed tomography (CT) and magnetic resonance imaging (MRI) features of acinar cell carcinoma of the pancreas and to correlate them with pathological findings to determine the unique imaging manifestations of this rare subtype tumour of the pancreas.

MATERIALS AND METHODS

From January 1986 to August 2008, six patients (five men and one woman, mean age 61.3 years) with histologically proven acinar cell carcinoma of the pancreas underwent CT (n=6) and MRI (n=4) examinations. The imaging features of each tumour were documented and compared with pathological findings.

RESULTS

The tumours were distributed in the head (n=4), body (n=1), and tail (n=1) of the pancreas. Four masses (67%) were uniformly or partially well-defined with thin, enhancing capsules. Central cystic components were found in five tumours (83%). Two tumours (33%) exhibited intratumoural haemorrhage, and one tumour (17%) had amorphous intratumoural calcification. In both CT and MRI, the tumours enhanced less than the adjacent normal pancreatic parenchyma. The signal intensity on MRI was predominantly T1 hypointense and T2 iso- to hyperintense.

CONCLUSION

Acinar cell carcinoma of the pancreas has distinct imaging features, and both CT and MRI are useful and complementary imaging methods.

Sonographic appearance of focal fatty infiltration of the pancreas

We report the sonographic, CT, and MRI findings in a case of focal fatty infiltration of the pancreas. Sonography revealed an echogenic mass in pancreas head. On CT, the mass was hypodense. The mass showed same signal intensity to the surrounding normal pancreas on in-phase T1-weighted MR images and a loss of signal intensity on opposed-phase MR images.

Intraoperative ultrasound of the pancreas

Intraoperative ultrasound provides spatial resolution of the pancreas superior to computed tomography, magnetic resonance imaging, and transabdominal sonography. This pictorial essay will review common benign and malignant pancreatic processes including the following: pancreatic ductal adenocarcinoma, pancreatitis, endocrine tumors, mucinous cystic neoplasm, intraductal papillary mucinous neoplasm, serous cystadenoma, and solid pseudopapillary tumor. The use of intraoperative ultrasound in specific surgical situations will be discussed, which include the following: (1) identification of insulinoma(s) which are not detectable preoperatively, (2) identification of the pancreatic duct to determine dissection planes for chronic pancreatitis surgery (eg, Puestow procedure) and for tumor resection, and (3) staging purposes for malignant disease.

Value of ultrasound examination in differential diagnosis of pancreatic lymphoma and pancreatic cancer

AIM: To investigate the value of clinical manifestations and ultrasound examination in the differential diagnosis of pancreatic lymphoma and pancreatic cancer.

METHODS: The clinical and ultrasonic characteristics of 12 cases of pancreatic lymphoma and 30 cases of pancreatic cancer were retrospectively analyzed.

RESULTS: Statistically significant differences were found in the course of disease, back pain, jaundice, carcino-embryonic antigen (CEA) and CA19-9 increase, palpable abdominal lump, superficial lymph node enlargement, fever and night sweats, lesion size, bile duct expansion, pancreatic duct expansion, vascular involvement, retroperitoneal (below the renal vein level) lymph node enlargement, and intrahepatic metastasis between pancreatic lymphoma and pancreatic cancer. There were no significant differences in age of onset, gender ratio, weight loss, nausea and vomiting, lesion position, the echo of the lesion, and the blood flow of the lesion.

CONCLUSION: Pancreatic lymphoma should be considered for patients with long lasting symptoms, superficial lymph node enlargement, palpable abdominal lump, fever and night sweats, relatively large lesions, and retroperitoneal (below the level of the renal vein) lymph node enlargement. A diagnosis of pancreatic cancer should be considered more likely in the patients with relatively short disease course, jaundice, back pain, CEA and CA19-9 increase, relatively small lesions, bile duct expansion, obvious pancreatic duct expansion, peripheral vascular wrapping and involvement, or intrahepatic metastases.