S3384 Mesenteric Panniculitis, Tamoxifen, and Severe Necrotizing Pancreatitis

Introduction: Tamoxifen is a selective estrogen receptor modulator medication primarily used to treat breast cancer particularly estrogen receptor positive. Tamoxifen induced pancreatitis is a rare entity which can be difficult to diagnose. Here we present a case report of a patient who was started on tamoxifen for mesenteric panniculitis and had an episode of severe pancreatitis which then evolved into necrotizing pancreatitis. Case Description/Methods: A 72-year-old man initially presented with cramping abdominal pain. A computed tomography scan of the abdomen and pelvis revealed mesenteric panniculitis. Following a course of prednisone prescribed by gastroenterology, the patient was referred to hematology to rule out non-Hodgkin lymphoma and started on tamoxifen for persistent abdominal pain. Three months later, he presented to the emergency room with severe acute abdominal pain and was admitted for severe acute pancreatitis with markedly elevated liver enzymes. Initial lipase was 2012 with creatinine: 1.09, AST: 232, ALT: 296, ALP: 60, Bilirubin: 7.3, calcium: 8.4, triglycerides 184. No alcohol history was reported. After a 2-week hospitalization, he was discharged. Four weeks later, the patient was readmitted with walled-off necrosis of the pancreas and fistulization into the stomach which was treated with a lumen apposing metal stent procedure. The patient remained admitted for another 2 weeks but ultimately made full recovery. The culprit factor was determined to be Tamoxifen due to temporal relationship and lack of other risk factors. Discussion: Mesenteric panniculitis, also known as mesenteric lipodystrophy or sclerosing mesenteritis, is an uncommon condition affecting the bowel mesentery, marked by inflammation, fat necrosis, and fibrosis. Standard treatments involve steroids, tamoxifen and immunosuppressants such as azathioprine, rituximab, cyclophosphamide, infliximab, and methotrexate. A 2024 review by Hussain et al. documented approximately 26 cases of tamoxifen-induced pancreatitis with hypertriglyceridemia. While elevated triglyceride levels, often a consequence of tamoxifen-induced dyslipidemia, are frequently observed in these cases, in some of the documented patients no hypertriglyceridemia was observed indicating a direct injury to pancreas by tamoxifen. Tamoxifen is a well tolerated drug but pancreatitis can be a life threatening adverse effect of the medication. High index of suspicion should be maintained for patients on Tamoxifen therapy regardless of duration of use for prompt recognition and management.