Solitary splenosis mimicking retroperitoneal tumor: a case report.

Introduction: Splenosis is a rare benign disorder characterized by autotransplantation of splenic tissue after splenic trauma or splenectomy. Isolated retroperitoneal splenosis is extremely uncommon and can be easily misdiagnosed as a malignant neoplasm, which may lead to unnecessary surgical procedures. Case presentation: A 38-year-old woman with a history of traumatic total splenectomy 6 years earlier was admitted with acute right upper abdominal pain. Imaging examinations showed cholecystolithiasis, choledocholithiasis, and a 2.2 cm solid mass in the right retroperitoneum at the upper pole of the right kidney, which was initially considered a neoplastic lesion. Laparoscopic resection was performed, and pathological examination confirmed splenosis. Clinical discussion: Retroperitoneal splenosis tends to show nonspecific imaging features similar to those of malignant tumors. For patients with a history of splenic injury or splenectomy, splenosis should be routinely included in the differential diagnosis of retroperitoneal masses. 99mTc-labeled heat-damaged red blood cell scintigraphy serves as a reliable noninvasive method for preoperative confirmation. Conclusion: Isolated splenosis in the right retroperitoneum at the upper pole of the right kidney is a very rare entity that mimics a retroperitoneal tumor. Splenosis should be suspected in patients with prior splenic trauma or splenectomy who present with unusual soft-tissue masses to avoid misdiagnosis and redundant surgery.