A Gastrointestinal Stromal Tumor (GIST) and a Pseudocyst of the Pancreas: A Peculiar Case of Both Co-existing in the Same Patient

Abstract

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasms of the gastrointestinal (GI) tract, typically originating from the interstitial cells of Cajal. The clinical presentations are variable according to their size and shape but rarely present as a palpable abdominal mass. Pancreatic pseudocysts are common complications of chronic pancreatitis characterized by fluid collections surrounded by a non-epithelialized wall of fibrous and granulation tissue. Patients may present with non-specific symptoms like abdominal pain, nausea, and vomiting and they generally have a history of acute pancreatitis. Small pseudocysts often resolve spontaneously, but larger ones often become symptomatic and may lead to complications. It is rare to find both a GIST of the stomach and a pseudocyst of the pancreas in the same patient. We present a unique case of a giant GIST and a pancreatic pseudocyst in a 72-year-old male who was experiencing abdominal pain and distension. Imaging revealed a massive lesion originating from the posterior gastric wall, which resembled a pseudocyst, along with a distinct cystic lesion adjacent to the pancreatic body. During surgical exploration, a complex interplay of both pathologies was discovered, requiring a comprehensive resection approach. The successful outcome highlights the importance of careful evaluation and personalized management in such rare cases.

Keywords: cyst; gastrointestinal stromal tumor (gist); mesenchymal tumors; pancreatic pseudocyst; stomach.

Figure 1. Pre-operative images of the abdomen (A) Front view and (B) lateral view.

Figure 2. Intra-operative images. (A) Intra-operative mass arising from the posterior wall of the stomach. (B) Distal pancreatectomy done for the pseudocyst arising from the body and tail of the pancreas. (C) After resection of the intra-operative mass.

Figure 3. GIST arising from the posterior wall of the stomach. (A) Section from the gastric mass showing normal compressed gastric mucosa at one end and the tumor arising in the submucosa and muscularis propria. (B) The tumor is composed of cells arranged in nodules separated by fibrous stroma. (C) The cells are immunopositive for cKIT. (D) The tumor cells are immunopositive for DOG1.

GIST: Gastrointestinal stromal tumor

Figure 4. Pseudocyst arising from the body and tail of the pancreas. (A) A section of the cyst shows a fibro-collagenous wall. (B) The cyst does not have a lining epithelium. Its lumen shows inflammatory granulation tissue, plasma cells, and histiocytes.