Radiologists play a key role in establishing an early and accurate diagnosis, especially for rare diseases. Mahvash disease (OMIM 619290) is an autosomal recessive hereditary disease caused by inactivating mutations of the glucagon receptor and its main clinical consequences are pancreatic neuroendocrine tumors and in some cases, porto-sinusoidal vascular disease and portal hypertension. Untreated Mahvash disease can be lethal. The diagnosis of Mahvash disease has almost always been delayed in the past due to radiologists\' unawareness of or unfamiliarity with the unique imaging features of Mahvash disease which are moderately to enormously enlarge pancreas with preserved pancreas contour and parenchyma without vascular involvement or lymphadenopathy. These features help differentiate Mahvash disease from other etiologies of diffusely enlarged pancreas such as diffuse pancreatic ductal carcinoma, diffuse pancreatic lymphoma, and autoimmune pancreatitis. Invoking Mahvash disease in the differential diagnosis of an enlarged pancreas has recently been shown to facilitate early diagnosis. To prevent missing the diagnosis of this significant disease, I sincerely ask radiologists to consider Mahvash disease in their differential diagnoses of diffusely enlarged pancreas.

OBJECTIVE: The objective of this study was to preliminarily assess the ability of metabolic parameters and radiomics derived from 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) to distinguish mass-forming pancreatic lymphoma from pancreatic carcinoma using machine learning.
METHODS: A total of 88 lesions from 86 patients diagnosed as mass-forming pancreatic lymphoma or pancreatic carcinoma were included and randomly divided into a training set and a validation set at a 4-to-1 ratio. The segmentation of regions of interest was performed using ITK-SNAP software, PET metabolic parameters and radiomics features were extracted using 3Dslicer and PYTHON. Following the selection of optimal metabolic parameters and radiomics features, Logistic regression (LR), support vector machine (SVM), and random forest (RF) models were constructed for PET metabolic parameters, CT radiomics, PET radiomics, and PET/CT radiomics. Model performance was assessed in terms of area under the curve (AUC), accuracy, sensitivity, and specificity in both the training and validation sets.
RESULTS: Strong discriminative ability observed in all models, with AUC values ranging from 0.727 to 0.978. The highest performance exhibited by the combined PET and CT radiomics features. AUC values for PET/CT radiomics models in the training set were LR 0.994, SVM 0.994, RF 0.989. In the validation set, AUC values were LR 0.909, SVM 0.883, RF 0.844.
CONCLUSIONS: Machine learning models utilizing the metabolic parameters and radiomics of 18F-FDG PET/CT show promise in distinguishing between pancreatic carcinoma and mass-forming pancreatic lymphoma. Further validation on a larger cohort is necessary before practical implementation in clinical settings.

Acute pancreatitis is a common gastroenterological condition that can occur due to several causes. While not required for diagnosis, imaging is often performed and may reveal unexpected findings such as pancreatic masses. Malignancies such as lymphoma are uncommon causes of acute pancreatitis, especially as the initial presentation of malignancy. We present a case of a young patient with acute pancreatitis caused by diffuse large B-cell lymphoma with extranodal disease secondarily involving the pancreas. Our case highlights the importance of keeping a broad differential for acute pancreatitis and considering rare etiologies such as pancreatic lymphoma in patients without another obvious culprit.

Primary pancreatic lymphoma is a rare disease that can mimic acute pancreatitis. Since the prognosis and approaches differ, clinicians should differentiate it from other pancreatic diseases, especially autoimmune pancreatitis and adenocarcinoma.

BACKGROUND: Pathological examination by endoscopic ultrasonography-guided fine-needle aspiration (EUS-FNA) has been reported to be useful in diagnosing pancreatic malignant lymphoma (ML), but some ML cases are difficult to be differentiated from pancreatic ductal adenocarcinoma (PDAC).
METHODS: This retrospective study included 8 patients diagnosed with ML that had a pancreatic-head lesion at initial diagnosis and 46 patients with resected PDAC in the pancreatic head between April 2006 and October 2021 at our institute. ML and PDAC were compared in terms of patients\' clinical features and imaging examinations.
RESULTS: The median tumor size was larger in ML than in PDAC (45.8 [24-64] vs. 23.9 [8-44] mm), but the median diameter of the caudal main pancreatic duct (MPD) was larger in PDAC (2.5 [1.0-3.5] vs. 7.1 [2.5-11.8] mm), both showing significant differences between these malignancies (both, P < 0.001). In the analysis of covariance, MLs showed a smaller caudal MPD per tumor size than PDACs, with a statistical difference (P = 0.042). Sensitivity and specificity using sIL-2R ≥ 658 U/mL plus CA19-9 < 37 U/mL for the differentiation of ML from PDAC were 80.0% and 95.6%, respectively.
CONCLUSIONS: Diagnosing pancreatic ML using cytohistological examination through EUS-FNA can be difficult in some cases. Thus, ML should be suspected if a patient with a pancreatic tumor has a small MPD diameter per tumor size, high serum sIL-2R level, normal CA19-9 level. If the abovementioned features are present and still cannot be confirmed as PDAC, re-examination should be considered.

暂无摘要。

Pancreatic masses are commonly encountered entities in radiology practice. Pancreatic ductal adenocarcinomas (PDAC) are the commonest pancreatic malignancies that typically present as infiltrative hypodense focal masses in the pancreatic head, which are hypoattenuating to the pancreatic parenchyma on pancreatic parenchymal and venous phases. However, there are various atypical imaging features of PDACs that create a diagnostic dilemma like tumor in body or tail, diffuse glandular involvement, isoattenuating tumors, cystic changes, or calcifications. Also, few relatively uncommon pancreatic malignancies like pancreatic neuroendocrine tumors, cystic pancreatic tumors, pancreatic lymphoma, and pancreatic metastases present with overlapping features. Accurate radiological characterization of pancreatic masses is important for optimal management and prognostication. Thus, it is imperative for radiologists to be aware of all the uncommon presentations of common pancreatic lesions and common presentations of uncommon pancreatic lesions to avoid erroneous interpretations and establishing the correct diagnosis.

Primary pancreatic lymphoma is a rare disease. It comprises less than 0.5 % of pancreatic neoplasm and 0.1% of malignant lymphoma. It should be differentiated from pancreatic adenocarcinoma because management differs. At computed tomography, 2 types of morphology of primary pancreatic lymphoma have been described- a localized well-circumscribed tumoral form and another diffuse enlargement infiltrating or replacing most of the pancreatic gland. Here, we are presenting computed tomography (CT) imaging features of a case of primary pancreatic lymphoma in a 27 year old female who presented with a complaint of abdominal pain radiating to the back for 3 months and yellowish discoloration of sclera and skin for the last 15 days. In contrast-enhanced computed tomography an exophytic homogenously hypoenhancing mass arising from head and neck region of pancreas was seen. Involvement of common bile duct (CBD) and duodenum was there. The main pancreatic duct was not dilated. Common hepatic artery was encased by mass without arterial luminal narrowing or distortion. Diagnosis of primary pancreatic lymphoma was suggested on basis of imaging findings and further confirmed with fine-needle aspiration cytology.

Although primary pancreatic lymphoma is a rare cause of pancreatic mass, this diagnosis should be considered during work-up. Furthermore, when adequate diagnostic material is available from biopsy, complete workup of the lymphoma, including not only type but also subtype when applicable, should be performed.

Primitive malignant pancreatic non-Hodgkin\'s lymphoma (NHL) is an extremely rare site of extranodal NHL, accounting for less than 0.7% of all NHLs and less than 0.5% of malignant pancreatic tumors. It mainly affects the elderly and very rarely the young subject (hence the interest in our case). Clinical diagnosis is difficult because it mimics pancreatic adenocarcinoma and chronic pancreatitis. We report the case of a 25 year old patient, treated for diffuse primary pancreatic large B-cell NHL revealed by epigastralgia with fulminating jaundice characterised by acute onset associated with alteration of the general state. NHL was diagnosed by biopsy of the duodeno-pancreatic cavity. Diagnosis and early treatment of these aggressive tumors enable remarkable improvements in prognosis.