Surgical Excision of a Giant Mature Retroperitoneal Teratoma Encasing the Superior Mesenteric Artery: A Case Report and Review of the Literature

Introduction: Teratomas are uncommon tumors derived from all three embryonic germ layers. Primary retroperitoneal teratomas (PRT) constitute 1-11% of retroperitoneal tumors and are most often seen in neonates and young adults. This case report presents a rare instance of a massive mature retroperitoneal teratoma in a 16-year-old female, which uniquely encased the superior mesenteric artery (SMA).

Case Presentation: A 16-year-old girl presented with back pain and an abdominal lump. Clinical examination and computed tomography (CT) revealed a 16.4x9.3x10.9 cm retroperitoneal mass containing fat, cystic elements, and calcifications. The mass displaced surrounding organs and encased the proximal SMA but did not invade other structures such as the inferior vena cava (IVC) or renal arteries. Tumor excision was performed via laparotomy. During surgery, the tumor was meticulously dissected from the SMA, IVC, and surrounding vessels. The surgery was uneventful, with minimal blood loss and no complications. The patient had an uneventful postoperative recovery and was discharged on the fifth postoperative day. Histopathological analysis confirmed the diagnosis of a mature cystic teratoma, with no evidence of malignancy.

Discussion: PRT is a rare extragonadal tumor often found in the midline structures Although mostly benign, malignant transformation is possible in 1-2% of cases, more so in adults. Radiological imaging, particularly CT and MRI, plays a crucial role in diagnosing and planning the surgical approach. Surgical excision is the gold standard for treatment. The uniqueness of this case lies in the tumor’s large size and its encasement of the SMA, which has not been previously reported.

Conclusion: Primary retroperitoneal teratomas are rare, and this case represents a unique presentation of a giant mature teratoma encasing the SMA. Preoperative imaging and meticulous surgical dissection are essential for successful management. This case highlights the importance of careful surgical planning in complex cases involving vital vascular structures.