Pancreatic lymphoma

Pancreatic lymphoma is most commonly a B-cell sub-type of non-Hodgkin lymphoma.

Epidemiology

Pancreatic lymphoma is typically seen in middle-aged patients with a mean age of around 55 years old and is more common in immunocompromised patients.

Clinical presentation

Symptoms are often non-specific but may include ¹:

• abdominal pain ~ 85%
• mass ~ 60%
• weight loss ~ 50%
• obstructive jaundice ~ 40% of cases
• acute pancreatitis 10% 

The classic B-symptoms of non-Hodgkin lymphoma (e.g. fever, chills, night sweats) are present in only 2% of cases ^1,2.

Pathology

Etiology

It is classified as either primary or secondary:

• primary pancreatic lymphoma is a rare extranodal manifestation of any histopathologic subtype of B-cell non-Hodgkin's lymphoma, representing <2% of extranodal lymphomas and 0.5% of pancreatic tumors ^1,2
• secondary lymphoma: found in 30% of non-Hodgkin lymphoma patients with widespread disease, it is the dominant form and is the result of direct extension from peripancreatic lymphadenopathy ¹

Location

Two morphologic patterns of pancreatic lymphoma are recognized ¹:

• focal form: occurs in the pancreatic head in 80% of cases and has a mean size of 8 cm
• diffuse form: infiltrative, leading to glandular enlargement and poor definition, features that can simulate the appearance of acute pancreatitis

Radiographic features

CT

• minimal enhancement
• peripancreatic lymph node enlargement
• it typically has uniform low attenuation
• diffuse enlargement (diffuse form) may simulate acute pancreatitis
• encasement of the peripancreatic vessels may occur; vascular invasion is less common in lymphoma than in adenocarcinoma ^1-2

MRI

• focal form: low signal intensity on T1-weighted images and intermediate signal intensity on T2-weighted images (slightly higher signal intensity than the pancreas but lower signal intensity than fluid), and shows faint contrast enhancement ¹
• diffuse form: low signal intensity on T1- and T2-weighted MR images and shows homogeneous contrast enhancement, although small foci of reduced or absent enhancement are sometimes seen ¹

Treatment and prognosis

Percutaneous or endoscopic core biopsy should be performed to establish the diagnosis ².

Pancreatic lymphoma carries a better prognosis than adenocarcinoma because first-line treatment with chemotherapy is generally effective in producing long-term disease regression or remission. Surgery is not required in most cases ¹.

Using complex treatment approaches, cure rates of up to 30% are reported for patients with primary pancreatic lymphoma. This prognosis is much better than the dismal 5% 5-year survival rate in patients with pancreatic adenocarcinoma ².

Differential diagnosis

Imaging differential considerations include

• acute pancreatitis
• pancreatic adenocarcinoma ³

For a diffuse bulkiness to the pancreas consider

• autoimmune pancreatitis