Lymphoma Mimicking Pancreatic Adenocarcinoma: A Case Report

Introduction

Malignant tumors of the pancreas are largely adenocarcinomas. Non-Hodgkin's lymphoma (NHL) is often caused by the lymphatic system. In the NHL, the gastrointestinal tract is the area of extranodal involvement (1). Pancreatic lymphoma is very rare and occurs below <1%. Because clinical signs and symptoms are similar to pancreatic adenocarcinoma, diagnosis of pancreatic lymphoma is usually very difficult (2). We aimed to present Magnetic Resonance (MR) findings of a pancreatic lymphoma case micking pancreatic adenocarcinoma.

Case Presentation

Magnetic Resonance Imaging (MRI) was performed for the differential diagnosis of a massive lesion with no contrast enhancement, which was hypodense compared to pancreas parenchyma in dynamic liver CT uncontrolled and post contrast all phases. With MRI, T₁A and T₂A coronal images of the patient were obtained, and diffusion and IV contrast postdynamic images were obtained.

Dynamic pancreatic MR examinations were performed with the diagnosis of abdominal pain and mass on the abdomen, and a lobular contoured mass irregularly limited hypodense lesion (Figure-1) in the CT examination.

T₂x hyper intense (Figure-3), T₂A hyper intense (Figure-3), duodenum compression and adjacent vascular structures surrounding the main portal vein and celiac trunks, and heterogeneous contrast at late phase in post contrast study with lobulated contour showing involvement (Figure-4). The described lesion included areas showing diffuse restriction in diffusion imaging (Figure-5).

Discussion

Pancreas-secreting lymphoma is rare, with an extranodal involvement of less than 1% (2). There are various pathologic subtypes such as primary pancreatic lymphoma follicular lymphoma, diffuse large B-cell lymphoma, mucosal-associated lymphoma and T-cell lymphoma. Clinical signs and symptoms are very similar, but it is an important finding that the pancreatic lymphoma is uneventful without jaundice (3). Our case was pathologically diagnosed as Diffuse B-cell lymphoma and there were no jaundice findings. Hypodense is seen as shomogen solid lesions in the noncontrasted sections. MRI is also seen in two types. In T1AGs, the signal intensity is a welldefined homogeneous mass with low signal intensity and heterogeneous signal increases in mild to moderate T₂AG. In the second type, low signal intensities are seen on T₁W and T₁W T₂W according to the pancreatic gland and mild moderate contrasting is seen on contrastenhanced examinations (1). The current case was more compatible with the first type and showed moderate contrast enhancement in late venous phase. Adenocarcinoma should be considered primarily in the differential diagnosis of pancreatic lymphoma. In a single primer pancreatic lymphoma the mass is usually larger than a typical adenocarcinoma. Adeno carcinoma rarely causes vessel stenosis or occlusion (1). In our case, obstruction was not present in the stricture other than being pushed into the veins. Diffusion-weighted imaging may vary with the cognitive necrotic areas it contains in pancreatic adenocarcinoma. Low ADC values depend on the fibrotic component and high cellularity it contains and cause restriction in the diffusion. Necrotic areas are a more common finding in angina pancreatic adenocarcinoma (4). In our case, there was diffusion restriction without necrosis with low ADC values parallel to increased cellularity. Apart from these, the table in the distinction between lymphoma and adenocarcinoma is helpful in other findings (3).

Conclusion

Although pancreatic lymphoma is very rare, it should be kept in mind in differential diagnosis in patients with a limited number of welldefined homogeneous internal structures and late phase contrast enhancement, vascular versus ductal obstruction, and clinical absence of jaundice. Biopsy is necessary for definitive diagnosis. It is useful to know that MRI and diffuse MRI in pancreatic lymphoma may provide useful information as well as diffuse restriction in both due to adenocarcinoma and lymphoma elevated cellularity.