A case of duodenal malignant lymphoma presenting as acute pancreatitis: systemic lupus erythematosus and immunosuppressive therapy as risk factors.

A 49-year-old man was admitted to our hospital with pancreatitis. He was diagnosed with systemic lupus erythematosus at 34 years of age and was being treated with oral tacrolimus (3 mg/day) and predonine (10 mg/day) for the past 15 months. The computed tomography (CT) scan showed the mass lesion had invaded the pancreatic head via thickening of the duodenal wall. Upper gastrointestinal endoscopy showed the all-round ulcerative lesion from the superior duodenal angle to the descending portion. Histological examination confirmed the diagnosis of diffuse large B cell lymphoma (DLBCL). Tacrolimus therapy was stopped due to the possibility of immunodeficiency-related lymphoproliferative disease; however, the lesion did not improve. Consequently, he was administered rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP). After six courses of R-CHOP therapy, a partial response was confirmed on CT. One month after the completion of chemotherapy, a gastrojejunal anastomosis was performed because of duodenal stenosis. He has since been well without recurrence. It was difficult to identify the risk factor for DLBCL; therefore, both the disease activity and immunosuppressive therapy should be taken into consideration as carrying a risk. In the present case, the symptom of pancreatitis enabled an early diagnosis of DLBCL.