Case report of a fibrin-associated large B-cell lymphoma presenting as a retroperitoneal cystic tumour mimicking an atypical pheochromocytoma

This report delineates a case of a 53-year-old male with a fibrin-associated large B-cell lymphoma (FA-LBCL) who initially presented with a large right upper quadrant mass, radiologically suggestive of an 18.6 cm retroperitoneal cystic lesion and biochemically mimicking an atypical pheochromocytoma. The patient underwent laparotomy and removal of the cystic tumour containing 2.5 L of fluid. Final surgical pathology confirmed FA-LBCL, demonstrating the first case of a retroperitoneal cystic FA-LBCL with biochemical changes mimicking an atypical pheochromocytoma.