Primary pancreatic lymphoma (PPL) is a rare disease that accounts for only 0.1% of malignant lymphomas, 0.6% of extranodal lymphomas, and 0.2% of all primary cancers that occur in the pancreas. While varying definitions of PPL have been suggested, criteria provided by the World Health Organization maintain that to meet a diagnosis of PPL, the following diagnostic criteria must be observed: the bulk of the disease is localized in the pancreas; and while adjacent lymph node involvement and distant spread may occur, the main clinical presentation must involve the pancreatic gland.
PPL can manifest in patients of all ages but it is more common in older adults and has a higher incidence in men. Those who are immunosuppressed due to HIV infection or solid organ transplantation are also at a higher risk for developing the disease. Clinicians may have difficulty making a diagnosis, as the initial symptoms may overlap with those of other pancreatic diseases. These include fever, night sweats, and weight loss. Some patients may also present with jaundice and/or gastric or duodenal obstruction.
Because it is such a rare disease, the optimal diagnostic and therapeutic protocols have not yet been established. In a study published in the European Journal of Hematology, researchers assessed the clinical, diagnostic, and histological characteristics, along with therapy and outcomes, in a series of 39 patients who received care at several institutions.
The main findings of their research included the association of PPL with high lactate dehydrogenase (LDH) levels (43% of cases), a normal rage of carbohydrate antigen 19-9 (CA19-19), and a relatively large mean tumor size (81 mm).
“The suspicion that a pancreatic mass could harbor a PPL should be advanced in case of elevated LDH values, normal CA19-9, a large tumor diameter, and the presence of distant lymphadenopathies,” the investigators wrote.
Lead author Davide Facchinelli, MD, Hematology Unit, Ospedale San Bortolo in Italy, pointed out that on imaging, PPL presents with features that are in common with pancreatic carcinoma but it also has some distinctive findings. “The majority of PPLs are large lesions with delayed homogeneous enhancement, peripancreatic fat stranding and vessel encasement, while vascular infiltration and pancreatic duct dilatation are rare in PPL,” he told Hematology Advisor.