Concurrent Incidental Presentation of Primary Retroperitoneal Follicular Lymphoma With Acute Pancreatitis

Background: Follicular lymphomas are a common type of non-Hodgkin’s lymphomas (NHL). Presentation varies widely from being asymptomatic to painless peripheral lymphadenopathy to classic B symptoms. We present an unusual case of follicular lymphoma where the patient initially presented with signs and symptoms of acute pancreatitis. The aim of this study is to recognize the challenges faced while diagnosing retroperitoneal NHL and the need for timely management of this disease. Case report: A 66-year-old Hispanic female with a medical history of treatment compliant asthma and hypertension presented to the ER with complaints of abdominal pain in the right upper quadrant with serum lipase >3000 U/L and elevated liver function tests (LFTs), aspartate aminotransferase (AST) 139 U/L, alanine aminotransferase (ALT) 65 U/L, alkaline phosphatase (ALP) 122 U/L. Abdominal ultrasound identified gall bladder wall thickening and dilation of biliary ducts. CT scan showed soft tissue mass in the retroperitoneum, measuring 9.3x4.8cm which wrapped around the aorta and pushed it off the spine. After two days of conservative management, her pain resolved and lipase levels normalized, she was discharged and scheduled for outpatient endoscopic ultrasound (EUS) with biopsy of the retroperitoneal mass. The next day, the patient presented to the ER with similar pain, and labs again showed elevated lipase, EUS, and fine needle biopsy of mass showed CD-10 positive B-cell lymphoma. The patient was discharged after the resolution of pain. A positron emission tomography (PET) scan four weeks after the initial CT scan showed an increase in tumor size without any metastatic lesions. While awaiting core biopsy, the patient presented to the ER for the third time with worsening abdominal pain, lipase >3000 IU/L, and ultrasound showing cholelithiasis with cholecystitis. The patient underwent laparoscopic cholecystectomy. Core needle biopsy of paraspinal lymph nodes showed grade 1-2 follicular lymphoma. Finally, the patient underwent six cycles of chemotherapy with Bendamustine and Rituximab and after the fourth cycle, a repeat CT scan showed resolution of adenopathy with minimal residual soft tissue attenuation in retroperitoneum. Discussion: NHL rarely occurs in retroperitoneum and its diagnosis is challenging. Our patient presented with the primary and unique occurrence of follicular lymphoma in the retroperitoneum. She presented with symptoms of an acute abdomen with elevated lipase and LFTs. She underwent multiple hospitalization and cholecystectomy before the correct diagnosis was made and until she was treated for follicular lymphoma. Conclusion: This study emphasizes the importance of being vigilant when a patient presents with unusual presentations of a disease in order to diagnose and treat the condition early to decrease the risk of complications and to mitigate the risk of poor outcomes.