Diagnostic and operative challenge of a giant non-pancreatic intra-abdominal pseudocyst: a rare case report.

Background: Large, non-pancreatic pseudocysts are rare pathologies that present as lesions in the intra-abdominal wall or peritoneal cavity. These cases can be diagnostically difficult, particularly in situations where fine-needle aspiration yields nonspecific cytology and imaging is also often nonspecific and nondiagnostic. These lesions may mimic hematomas, seromas, cystic neoplasms, and other bowel-related pathologies, which may require surgical excision for definitive diagnosis and curative treatment. Case Description: We present a case of a 73-year-old male with a body mass index of 43 who presented to the emergency department for a ureteral stone and was found on computed tomography (CT) imaging incidentally to have a large left lower quadrant abdominal wall mass. The lesion was highly vascularized and intimately adherent to both the abdominal wall and colon. Two separate biopsy results showed nonspecific cytology and hemorrhagic debris. Operative excision required tedious removal from the bowel and abdominal wall and evacuation of 3 L of fluid. Pathology results showed a chronic pseudocyst lacking an epithelial lining. Conclusions: The case demonstrates the diagnostic limitations of fine-needle aspiration and imaging, along with the potential for abdominal pseudocysts to mimic multiple differentials. Additionally, it highlights the importance of complete surgical excision for diagnostic and curative treatment.