Endoscopic retrograde pancreatographic findings of pancreatic lipomatosis

Quantitative imaging predicts pancreatic fatty infiltration on routine CT examination

PURPOSE

The purpose of this study was to assess the performance of quantitative computed tomography (CT) imaging for detecting pancreatic fatty infiltration, using the results of histopathological analysis as reference.

MATERIALS AND METHODS

Sixty patients who underwent pancreatic surgery for a pancreatic tumor between 2016 and 2019 were retrospectively included. There were 33 women and 27 men with a mean age of 56 ± 12 (SD) years (age range: 18-79 years). Patients with dilatation of the main pancreatic duct, chronic pancreatitis, or preoperative treatment were excluded to prevent any bias in the radiological-pathological correlation. Pancreatic fatty infiltration was recorded at pathology. Pancreatic surface lobularity, pancreatic attenuation, visceral fat area, and subcutaneous fat area were derived from preoperative CT images. The performance for the prediction of fatty infiltration was assessed using area under receiver operating characteristic curve (AUC) and backward binary logistic regression analysis. Results were validated in a separate cohort of 34 patients (17 women; mean age, 50 ± 14 [SD] years; age range: 18-73).

RESULTS

A total of 28/60 (47%) and 17/34 (50%) patients had pancreatic fatty infiltration in the derivation and validation cohorts, respectively. In the derivation cohort, patients with pancreatic fatty infiltration had a significantly higher PSL (P < 0.001) and a lower pancreatic attenuation on both precontrast and portal venous phase images (P = 0.011 and 0.003, respectively), and higher subcutaneous fat area and visceral fat area (P = 0.010 and 0.007, respectively). Multivariable analysis identified pancreatic surface lobularity > 7.6 and pancreatic attenuation on portal venous phase images < 83.5 Hounsfield units as independently associated with fatty infiltration. The combination of these variables resulted in an AUC of 0.85 (95% CI: 0.74-0.95) and 0.83 (95% CI: 0.67-0.99) in the derivation and validation cohorts, respectively.

CONCLUSION

CT-based quantitative imaging accurately predicts pancreatic fatty infiltration.

Quantification of pancreatic iron overload and fat infiltration and their correlation with glucose disturbance in pediatric thalassemia major patients

Background

Diabetes mellitus affects more than a quarter of patients with thalassemia major (TM) worldwide, and increases the risk for cardiac complications, contributing to significant morbidity. Pancreatic iron overload (IO) and fat infiltration have been correlated with this endocrinal complication in adult TM patients. It has been shown that in adult TM patients, iron accumulation and fat infiltration are found to be heterogeneous in the pancreatic head, body, and tail region. R2* and a fat fraction (FF) generated by gradient-echo imaging can be used as quantitative parameters to assess the iron and fat contents of the pancreas. This study aimed to determine the pattern of pancreatic iron accumulation and fat infiltration in pediatric TM patients with gradient-echo imaging and evaluate the association between pancreatic IO and fat infiltration and glucose disturbances.

Methods

A total of 90 children with TM (10.7±3.1 years) were included. All patients underwent pancreatic magnetic resonance imaging (MRI) using multi-echo gradient-echo sequences. IO was measured by R2* relaxometry in 90 patients, and FF values were measured using iterative decomposition of water and fat with echo asymmetry and the least-squares estimation (IDEAL) method in 40 patients. R2* and FF were assessed in the pancreatic head, body, and tail. The global R2* and global FF values were obtained by averaging the respective values from the pancreatic head, body, and tail. The correlations between global R2*, global FF, and fasting glucose were determined using Spearman's correlation analysis. The Friedman test was used to compare R2* and FF among different pancreatic regions. Receiver operating characteristic (ROC) analysis was used to determine the performance of global R2* and global FF in discriminating impaired fasting glucose from normal fasting glucose patients.

Results

The global R2* was positively correlated with the global FF in the pancreas (r=0.895, P<0.001). No significant differences were found in R2* among the 3 regions of the pancreas (χ²=4.050, P=0.132), but significant differences were found in FF among the 3 pancreatic regions (χ²=16.350, P<0.001). Both global pancreatic R2* (r=0.408, P<0.001) and global FF (r=0.523, P=0.001) were positively correlated with fasting glucose. ROC analysis showed that global pancreatic R2* and global FF had an area under the curve of 0.769 and 0.931 (both P<0.001), respectively, in discriminating between impaired and normal glucose function patients.

Conclusions

Pediatric TM patients can have homogeneous iron siderosis and heterogeneous fat infiltration in the pancreas as measured by gradient-echo imaging, both of which are risk factors for diabetes.

Extensive Fatty Replacement of the Pancreas (Pancreatic Lipomatosis) in a Dog

A 12-year-old neutered female mixed-breed dog was referred for occasional vomiting that had increased progressively in frequency over the past 3 months. Palpation of the abdomen revealed a firm mass of unknown aetiology, located within the cranial to mid abdomen, while abdominal surgical exploration revealed a well-defined abdominal mass of pancreatic origin. The pancreatic mass caused lateral displacement of the duodenum as well as medial displacement of the pylorus, resulting in impairment of pyloric outflow. Further examination revealed a firm, poorly vascularized and coarsely lobulated structure. The histopathological findings were consistent with severe pancreatic lipomatosis and atrophy. Immunohistochemically, the remnant pancreatic cells were positive for cytokeratins AE1/AE3 and glucagon, and negative for insulin. Routine follow-up with the referring veterinarian showed no evidence of postoperative complications, but the dog continued to deteriorate further and died despite medical management. Pancreatic lipomatosis is a rare condition in small animal practice. The aetiology or predisposing factors have not been identified in animals.

A case report on total pancreatic lipomatosis: An unusual entity

Total pancreatic lipomatosis (PL) is an unusual entity of pathologic significance and speculative origin. It refers to complete replacement of pancreatic parenchyma by fat cells. Fat replacement may vary from mild fatty infiltration to massive replacement of the pancreas by adipose tissue, resulting in malabsorption syndrome due to pancreatic insufficiency. We present a case of a 60-year-old elderly woman with atypical abdominal complaints, diabetes mellitus, weight loss, and steatorrhea. Abdominal computed tomograms were diagnostic of PL. Magnetic resonance imaging verified this impression. The patient improved clinically after the 8-week trial of high-dose oral pancreatic enzyme replacement therapy. There is a marked reduction of steatorrhea and weight gain. This case report focuses on pathophysiology, diagnosis, and treatment guidelines of PL.

Exploring the metabolic syndrome: Nonalcoholic fatty pancreas disease

After the first description of fatty pancreas in 1933, the effects of pancreatic steatosis have been poorly investigated, compared with that of the liver. However, the interest of research is increasing. Fat accumulation, associated with obesity and the metabolic syndrome (MetS), has been defined as “fatty infiltration” or “nonalcoholic fatty pancreas disease” (NAFPD). The term “fatty replacement” describes a distinct phenomenon characterized by death of acinar cells and replacement by adipose tissue. Risk factors for developing NAFPD include obesity, increasing age, male sex, hypertension, dyslipidemia, alcohol and hyperferritinemia. Increasing evidence support the role of pancreatic fat in the development of type 2 diabetes mellitus, MetS, atherosclerosis, severe acute pancreatitis and even pancreatic cancer. Evidence exists that fatty pancreas could be used as the initial indicator of “ectopic fat deposition”, which is a key element of nonalcoholic fatty liver disease and/or MetS. Moreover, in patients with fatty pancreas, pancreaticoduodenectomy is associated with an increased risk of intraoperative blood loss and post-operative pancreatic fistula.

Pancreatic Lipomatosis: An Extensive Pictorial Review

Pancreatic lipomatosis – also commonly called fat replacement – represents the most frequent benign pathologic condition of the adult pancreas. Most cases remain asymptomatic, and only some rare extreme degrees of lipomatosis or fat replacement may lead to exocrine pancreatic insufficiency.

The precise etiology of the entity remains unclear, and the condition has been found associated with several diseases comprising diabetes mellitus, metabolic syndrome, acquired or hereditary pancreatitis, alcoholic hepatitis, cystic fibrosis and condition comprising increasing age, body mass index, or more precisely visceral fat index, and use of steroid therapy. Numerous cases are also associated with condition compromising the permeability of the pancreas ductal system, such as intraductal calculus, pancreatic tumors, and congenital or experimental stenosis.

Uneven lipomatosis and fat replacement are also common presentations and responsible for the great diversity of imaging features. The reasons for uneven presentations are controversial and probably interweave embryologic or ductal hypotheses. Lipomatous pseudohypertrophy of the pancreas represents the most extreme situation of pancreatic lipomatosis and is considered, probably in a contestable way, as a rare, specific, and distinct entity.

We hereby present an extensive pictorial review of the broad spectrum of imaging features of this entity. The images are extracted from a compilation of cases collected in our department over more than a decade. We review and discuss the embryologic and ductal hypothesis, the differential diagnosis. Finally, we illustrate some unusual presentations and evolutions.

Pancreatic duct ligation after almost complete β-cell loss: exocrine regeneration but no evidence of β-cell regeneration

There has been great interest in the extent of β-cell regeneration after pancreatic duct ligation (PDL) and whether α- to β-cell conversion might account for β-cell regeneration after near-complete β-cell loss. To assess these questions, we established a PDL-model in adult male rats after almost complete beta-cell depletion achieved by giving a single high dose of streptozocin (STZ) in the fasted state. Because of the resultant severe diabetes, rats were given islet cell transplants to allow long-term follow-up. Although animals were followed up to 10 months, there was no meaningful β-cell regeneration, be it through replication, neogenesis, or α- to β-cell conversion. In contrast, the acinar cell compartment underwent massive changes with first severe acinar degeneration upon PDL injury followed by the appearance of pancreatic adipocytes, and finally near-complete reappearance of acini. We conclude that β-cells and acinar cells, although originating from the same precursors during development, have very distinct regenerative potentials in our PDL model in adult rats.

The clinical significance of pancreatic steatosis

More research is now focused on pancreatic steatosis. Multiple definitions, clinical associations and synonyms for pancreatic steatosis are described in the literature and can be confusing. The integration and comparison of several studies concerning this topic is therefore challenging. In the past, pancreatic steatosis was considered an innocuous condition, a bystander of many underlying diseases (such as congenital syndromes, hemochromatosis and viral infection). However, evidence that pancreatic steatosis (strongly associated with obesity and the metabolic syndrome) has a role in type 2 diabetes mellitus, pancreatic exocrine dysfunction, acute pancreatitis, pancreatic cancer and the formation of pancreatic fistula after pancreatic surgery is emerging. This Review focuses on the different etiological factors and the clinical consequences of pancreatic steatosis.

Rapidly progressive pancreatic lipomatosis in a young adult patient with transfusion-dependent myelodysplastic syndrome

Pancreatic lipomatosis is defined as deposition of fat cells in pancreatic parenchyma. Although the etiology of this condition is still unclear, it is not uncommon in the elderly, obese individuals, and a variety of transfusion-dependent hematologic diseases such as beta-thalassemia major. Pancreatic lipomatosis associated with transfusion-dependent myelodysplastic syndrome (MDS) has never been reported. We present a 17-year-old male patient with transfusion-dependent MDS. He received transfusion of a total of 345 units of blood in a period of 18 months but without iron chelating agent. Progressive fatty replacement of the pancreas parenchyma was found by a series of computed tomography images over seven hospital admissions due to repeated infections. Bone marrow biopsy revealed hemosiderin deposition. Because of his poor response to induction chemotherapy, stem cell transplantation was suggested, but the patient died of sepsis before the therapeutic procedure could take place. Although most patients with pancreatic lipomatosis have neither clinical symptoms nor abnormal laboratory data, it may cause endocrine and exocrine pancreas dysfunction. In this reported case, mild exocrine dysfunction was noted on the last admission. Clinicians should be cautious of hemosiderin deposition after large amount of blood transfusion and chelating therapy should be given to avoid iron overload.

Focal fatty replacement of the pancreas: usefulness of chemical shift MRI

OBJECTIVE

The purpose of this study was to describe the typical CT and chemical shift MRI findings and to evaluate their usefulness in the diagnosis of focal fatty replacement of the pancreas in five patients.

CONCLUSION

The presence of a perceptible focal low-attenuation lesion in the pancreas on CT and the reduction in signal intensity of the lesion on the opposed phase of chemical shift MR images are useful for differentiating focal fatty replacement of the pancreas from true pancreatic neoplasm. Therefore, these imaging findings obviate invasive diagnostic procedures and surgery in the care of patients with focal fatty replacement of the pancreas.