Diagnosis of Pancreatic Cancer: Can Biopsy Misguide?

Abstract

Pancreatic cancer remains the second leading cause of cancer related mortality in United States with 48,960 new cases and 40,560 deaths in 2015, with a 5 year survival rate of 7.2%. Due to its retroperitoneal location and insidious course, diagnosis of pancreatic cancer remains elusive. Case Presentation: 76 y/o male with past medical history of hypertension, diabetes and hypothyroidism presented with decreased appetite, 60 pound weight loss, fatigue and pale white stools for a year. Laboratory workup revealed AST and ALT ˜ 200 IU/L, ALP > 1200 IU/L, CEA - 9.9 ng/mL, CA-125 of 81.6 U/mL and CA 19-9 of 12131 U/mL. CT abdomen showed extrahepatic and intrahepatic ductal dilatation, narrowing of common bile duct, soft tissue density in the pancreatic head. (figure 1). EUS revealed a 3x2 cm heterogenous mass in pancreatic head encasing bile duct. FNA of the mass was suggestive of benign cellular elements. Repeat EUS-FNA of the mass was also negative for malignancy. During ERCP, sphincterotomy was performed with multiple biopsies of papilla, which were also negative for malignancy. PET scan was also negative for uptake anywhere (figure 2) Due to multiple co-morbidities he was managed supportively and external biliary drain was placed. Autopsy revealed poorly differentiated pancreatic cystadenocarcinoma with signet ring cells and mucinous infiltration involving pancreatic head and body. (figure 3).Figure 1Figure 2Figure 3Discussion: Algorithm for imaging diagnosis of pancreatic carcinoma includes a multi-detector computed tomography (MDCT), MRCP, or fine-needle aspiration using EUS. MDCT has >96% sensitivity for predicting the resectability of pancreatic cancer, however misses small metastases. EUS produces high resolution images of the pancreas and is useful for tumours < 3 cm. EUS-guided FNA is > 90% sensitive in detecting pancreatic malignancy. In our case despite two EUS- FNA attempts, we were unable to get a tissue diagnosis, which highlights potential fallacies. The necessity of obtaining a cytological or tissue diagnosis of pancreatic cancer prior to surgery remains controversial. However in unresectable cases and where palliation is to be considered, pathological proof of malignancy is required for determining neo-adjuvant chemotherapy. This case highlights the fact that despite many advances we still have long strides to make in techniques for diagnosis of pancreatic cancer, to help institute timely management.