Atypical Presentation of Gastrointestinal Stromal Tumor as Multiple Intra-Abdominal Cysts: A Case Report.

Gastrointestinal stromal tumors (GISTs) are the most common nonepithelial solid neoplasms involving the alimentary tract. We report a case of cystic GIST with multiple cystic metastases. A 61-year-old man presented with upper abdominal pain for two months. Further evaluation revealed a large intra-abdominal cyst in the lesser sac and another cyst over the segment VII of the liver on imaging. Multiple intra-abdominal hydatidoses were suspected based on the imaging and its endemic nature in the geographical area. However, the hydatid serology was normal. In view of hemorrhagic cyst fluid, an intraoperative frozen biopsy of the cyst wall was done, which revealed features suspicious of a mesenchymal tumor. Sleeve gastrectomy with en-bloc excision of the gastric cyst, excision of the hepatic cyst, and complete excision of multiple other intra-abdominal cysts were performed considering GIST as a possibility. Histology revealed a clear cell variant of GIST. Gastric GISTs primarily presenting as multiple intra-abdominal cysts and of clear cell histological variants had never been reported in the literature. The patient was started on imatinib, and he has shown no evidence of recurrence after 12 months of follow-up. A high index of suspicion, intraoperative frozen section, meticulous surgery, and immunohistochemistry are all crucial for the effective management of atypical cases. GIST may be considered as a part of differential diagnosis in clinical scenarios with multiple intra-abdominal cysts, especially in the equivocal setting.