S1484 Masquerading Masses

Abstract

INTRODUCTION: Amongst isolated solid pancreatic masses identified radiologically in middle aged adults, common diagnoses rendered on histology include adenocarcinoma and neuroendocrine tumors. Ninety percent of all pancreatic solid masses are pancreatic adenocarcinomas which carry a grim prognosis. Herein, we present two cases of isolated solid pancreatic masses radiologically masquerading as carcinomas that highlight the importance of clinico-pathologic correlation in directing management of patients with pancreatic lesions. CASE DESCRIPTION/METHODS: Case 1 is of a 51-year-old male with benign prostatic hyperplasia who presented to his urologist for recurrent urinary tract infection. Computed tomography (CT) was performed and showed a 9.5 × 4.9 cm mass in the pancreatic body and tail concerning for adenocarcinoma. Magnetic resonance image (MRI) showed enhancing rind of soft tissue in the body and tail without peripancreatic vascular attenuation (Figure 1a) and endoscopic ultrasound (EUS) showed diffuse heterogeneous echogenicity suggestive of autoimmune pancreatitis. IgG4 serum levels were within normal range. Fine needle aspiration (FNA) of the mass showed a CD10+ B-cell lymphoproliferative disorder and final pathologic diagnosis of low-grade follicular lymphoma was rendered (Figure 2a). The patient is currently on chemotherapy and responding favorably. Case 2 is of a 70-year-old male who presented with abdominal discomfort. A CT abdomen and pelvis revealed a well-delineated 1.9 × 1.5cm distal pancreatic tail mass. MRI showed that the lesion was isointense to the spleen and pancreas with prominent solid arterial phase enhancement and moderate diffusion restriction suggestive of a neuroendocrine tumor. PET NETSPOT scan also supported a somatostatin receptor avid tumor. An EUS with FNA demonstrated benign splenic tissue consistent with the diagnosis of intrapancreatic accessory spleen (Figure 2b). DISCUSSION: Increased use of imaging has led to a growing number of identified pancreatic abnormalities. While ductal adenocarcinoma of the pancreas is commonly encountered in the presence of isolated solid pancreatic masses, rare malignant entities such as lymphoma and non-malignant entities such as intrapancreatic accessory spleen should remain on the differential diagnosis. These cases illustrate that despite characteristic radiologic findings, tissue diagnosis is prudent prior to management of any pancreatic lesion as consequences of erroneous therapy can be dire.Figure 1a.: MRI abdomen showing normal diameter pancreatic duct with thickening of pancreatic tail and encasement of splenic vein.Figure 2a.: Pancreatic body/tail mass biopsy showing small atypical lymphocytic infiltrate surrounding pancreatic parenchyma, immunophenotypically consistent with low grade follicular lymphoma.Figure 3b.: Pancreatic tail mass fine needle aspiration showing benign splenic tissue. CD8 highlights splenic sinusoidal cells in the secondary image.