Primary Pancreatic Lymphoma
Authors: Malin Elisabeth S. , Toomey Christiana E. , Ono Jill , Sohani Aliyah R. , Michaelson James S. , Barnes Jeffrey A. , Abramson Jeremy S. , Hochberg Ephraim P. 
Published: October 2019

Abstract
Abstract 4150

Introduction:
Primary extranodal pancreatic non-Hodgkin lymphoma (PPL) makes up no more than 0.16–4.9% of pancreatic malignancies and less than 0.7% of non-Hodgkin's lymphomas (NHL). Since lymphomas involving the pancreas may have a similar clinical presentation to primary pancreatic adenocarcinoma, and often have a similar radiographic appearance, pancreatic lymphoma is often not diagnosed until surgical exploration or definitive surgery for presumed pancreatic cancer. Preoperative distinction of adenocarcinoma and PPL is critical as the management and prognoses of these malignancies are mutually exclusive. The rarity of PPL has made epidemiologic studies difficult to conduct.

Methods:
We queried our IRB-approved clinicopathologic database, derived from comprehensive tumor registry data at the Massachusetts General Hospital, for all adult patients diagnosed with PPL between 2000 and 2010. The database contains 5821 patients with mature lymphoid malignancies. Cases were included in the analysis if they met clinicopathologic criteria for PPL, defined as dominant disease presentation within the body of the pancreas. Forty-five patients were found to have pancreatic involvement at initial presentation of whom 31 (68.9%) on further investigation had a pancreatic primary and are included in the analysis. For each patient, we collected complete demographic information, clinical presenting features, histology, chemotherapy regimens, use of radiotherapy, and type of surgical biopsy performed. We also collected outcome data including results of interim and final restaging scans.

Results:
PPL represented 0.5% of all mature lymphomas seen at our institution. The median age at diagnosis was 60 yrs (range 20–91). There were 21 male and 10 female patients. Eighteen patients had Diffuse Large B Cell Lymphoma (DLBCL) (one with a focus of follicular lymphoma (FL) grade 3), two each had Burkitts Lymphoma, FL Grade 1–2, and mantle cell lymphoma (MCL), and one each had small lymphocytic lymphoma (SLL), Hodgkin Lymphoma, Marginal zone lymphoma, and peripheral T cell Lymphoma not otherwise specified. Three patients had NHL not otherwise specified (NOS). Of the 31 patients, 13 patients were stage 4E, 5 were stage 3E, 8 were stage 2E, and 5 were Stage 1E. Seventeen patients presented with jaundice. In 2 cases clinical history at presentation was unavailable. Elevated lactate dehydrogenase (LDH) level was present in 18 of 26 patients (69%) for whom laboratory values were available. B symptoms were present at diagnosis in 13 patients, absent in 17 patients, and unavailable in 1. Diagnosis was made in sixteen patients by fine needle aspiration (FNA), in nine patients by core needle biopsy, in two by incisional biopsies, and four patients were diagnosed after a definitive pancreaticoduodenectomy (Whipple procedure). Information on therapeutic regimen was available for 24 patients. One of these 24 patients was treated with primary radiotherapy without chemotherapy for a grade 1–2 primary pancreatic FL. Twenty-three patients had initial chemotherapy: 8 with R-CHOP, 5 with CHOP, 2 with CVP, and 1 each with CHOP-14, CVP × 1 then CHOP, R-CVP, R-EPOCH, R-CODOX-M/R-IVAC, R-CDOP and R-CP then R-CHOP. One patient was treated with chemotherapy not otherwise specified in the medical record. Four of these 23 patients received consolidative radiotherapy after initial therapy. Chemotherapy had significant efficacy with an overall response rate (ORR) of 75% in all chemotherapy treated patients (10 CR, 8 PR). Therapy information was available on 13 patients with DLBCL with an ORR of 85% (7 CR, 4 PR) to R-CHOP in 8 patients, CHOP in 3, and 1 each R-EPOCH and R-CDOP. One patient died of meningeal relapse of DLBCL despite therapy with R-EPOCH. For the entire PPL group at median follow-up of 28.5 months, the progression free and overall survivals are 48.4% and 64.5%, respectively. At a median follow-up of 33.4 months, the progression free and overall survivals for the DLBCL-PPL group are 50.0% and 66.7%, respectively.

Discussion:
PPL is a rare extranodal presentation of lymphoma accounting for 0.5% of lymphomas seen at a tertiary referral center. Pre-surgical diagnosis of PPL is critical to avoidance of unnecessary major surgery. The outcome of PPL approximates the outcome of DLBCL in other sites. An increased rate of CNS relapse was not seen with presentations in this extranodal site.

Disclosures:
Hochberg: Biogen Idec: Speakers Bureau; Genentech: Speakers Bureau; Enzon Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Amgen: Speakers Bureau; WorldCare: Membership on an entity's Board of Directors or advisory committees; Proventys: Consultancy.