S2924 Ruptured GIST Mimicking Hemosuccus Pancreatitis

Abstract

INTRODUCTION: Gastrointestinal stromal tumors (GIST) are the most common non-epithelial tumors occurring in the gastrointestinal tract. Even though they are usually solid, they can appear as cystic lesions on imaging leading to a difficult diagnosis. We present a case of a GIST that was initially diagnosed as a pancreatic pseudocyst after extensive work-up. CASE DESCRIPTION/METHODS: A 61-year-old man with no past medical history presented to the ED with abdominal pain after sustaining blunt trauma to the abdomen. Abdominal CT showed a 16 cm left upper quadrant mass with central necrosis and perigastric adenopathy, but no other imaging to compare (Figure 1). During EUS evaluation a thick ring with a central cystic core was noted between the stomach and tail of pancreas. Given this location, traumatic pseudocyst was thought likely. Although the thick wall was somewhat unusual, FNA results were consistent with pseudocyst. PET scan was then performed showing a cystic mass with circumferential heterogenous and mildly increased FDG activity but no adenopathy, supporting a diagnosis of pseudocyst (Figure 2). Unfortunately, the patient was lost to follow up.Eight months later, the patient came to the ED with epigastric abdominal pain associated with black tarry stools. He was tachycardic and the abdomen was distended and tender. Laboratory workup revealed a Hb of 7.1. A CT scan showed the large heterogeneous, cystic mass suggestive of hemorrhagic content as well as ascites (Figure 3). He was admitted to ICU, received 2 units of blood and started on IV pantoprazole. A paracentesis retrieved 1.75 L of hemorrhagic fluid which led to an initial diagnosis of Hemosuccus Pancreatitis. He was not deemed a surgical candidate due to the lesion location and poor nutritional status. A percutaneous catheter was inserted for symptomatic relief and a CT guided biopsy of the wall of the cystic mass was performed. The pathology results were consistent with GIST. DISCUSSION: EUS is a valuable method for evaluation of GISTs by assessing its morphology however, due to the heterogenous appearance, diagnosis can be challenging. Moreover, FNA can yield false negative results due to inadequate amount of tissue, especially if central necrosis is present. This patient's missed diagnosis eventually led to clinical worsening where further work-up was pursued to reveal the definitive diagnosis. GISTs should be considered in your differential despite exhaustive work-up as it may evade diagnosis due to its heterogeneity in morphology and presentation.Figure 1.: Abdominal CT scan on first admission showing a 16 cm enhancing left upper quadrant mass with central necrosis and perigastric adenopathy.Figure 2.: PET scan showing a cystic mass with circumferential heterogenous and mildly increased FDG activity but no adenopathy.Figure 3.: Abdominal CT scan on second admission showing the large heterogeneous, cystic mass suggestive of hemorrhagic content.