Primary pancreatic lymphoma or secondary involvement: what is the difference?

Primary pancreatic lymphoma is a very rare disease. On the other hand, secondary involvement of the pancreas from nearby lymph node disease is a common form of involvement. Whether primary pancreatic lymphoma or secondary involvement, this disease can present as a mass mimicking pancreatic carcinoma [1]. A 75-year-old woman presented with a three-month history of abdominal pain radiating to the back, nausea, vomiting and weight loss. Her past history was unremarkable except for diabetes of 5 years duration which was regulated with diet alone. Her laboratory tests upon admission were as follows: white blood cell count 20,700 mm (reference range: 4,000-11,000 mm ), hemoglobin 8.5 g/dL (reference range: 11.7-15.5 g/dL), lactate dehydrogenase 501 U/L (reference range: 240-480 U/L), glucose 216 mg/dL (reference range: 70-110 mg/dL), total protein 5.95 g/dL (reference range: 6.4-8.3), albumin 2.6 g/dL (reference range: 3.44.8 g/dL), beta-2-microglobulin 10,355 ng/mL (reference range: 609-2,366 ng/mL). The tumor marker levels of AFP, CEA; CA 125, CA 15-3 and CA 19-9 were all within the normal range. Abdominal computed tomography (Figure 1) revealed a mass in the pancreatic tail which could not be distinguished from the pancreas parenchyma and nearby surrounding soft tissues, with encasement of the splenic artery and vein, accompanied by splenic infarct and lymphadenopathies located at the portal hilus, para-aortic region and left renal hilus. To differentiate the origin of the pancreatic mass as an endocrine or an exocrine tumor, serotonin, 3-methoxytiramine, metanephrine, normetanephrine, vanyl mandelic acid, 5 hydroxy indole acetic acid and dopamine tests were performed and were found to be within normal levels. Percutaneous ultrasonographyguided biopsy of the suspicious peripancreatic node confirmed the diagnosis. Immunohistochemical studies of the biopsied tissue demonstrated large atypical lymphoid cells which were positive for CD20 with a Ki-67 index of 30%. The final diagnosis was diffuse large B cell lymphoma. Bone marrow aspiration and biopsy did not show any involvement of disease. The term extranodal lymphoma refers to non-Hodgkin lymphoma or Hodgkin disease in sites other than the lymphatic organs (spleen, thymus, etc.), which may represent up to 30-40% of all non-Hodgkin lymphoma cases [1, 2]. Extranodal lymphoma is classified as primary if the involvement is confined to a single organ and the adjacent lymph nodes whereas it is classified as secondary if there is involvement of nodes other than those in close proximity to the primary organ or the involvement of more than one extranodal site [2]. The stomach and the small intestine are the most common gastrointestinal sites for extranodal involvement. Secondary involvement of the pancreas from adjacent organs or peripancreatic lymph nodes is the prevalent presentation. Primary pancreatic lymphoma is a rare