Primary neuroendocrine tumor in the retroperitoneal cavity: A rare case report

Introduction and importance: Neuroendocrine tumors (NETs) are rare malignancies, accounting for a small percentage of gastrointestinal and bronchopulmonary cancers. Retroperitoneal NETs are infrequent and can be primary or metastatic. They are commonly metastatic rather than primary tumors, with primary retroperitoneal NETs being exceptionally rare. Case presentation: A 38-year-old woman presented with left flank pain persisting for one year, which had progressively worsened. Imaging revealed a large retroperitoneal mass exerting pressure on the stomach, spleen, liver, and upper pole of the left kidney. A biopsy of the tumor was done and the results were consistent with NET. The tumor, which measured approximately 19 x 12.5 x 11 cm, was surgically removed, and the pathological findings were consistent with the results of the biopsy prior to the surgery. Clinical discussion: Neuroendocrine tumors are rare and exhibit diverse characteristics based on location, size, hormone secretion, and metastasis. Retroperitoneal neuroendocrine tumors are typically metastatic and rarely primary. The extremely large size of the tumor in this case highlights the surgical challenges associated with retroperitoneal NETs. Imaging, such as CT and MRI, plays a crucial role in diagnosis. Conclusion: The study emphasizes the need to consider primary NETs as a possible cause of large retroperitoneal masses, especially if the tumor size is significant. Surgical resection is the primary treatment option with generally favorable outcomes. However, the size of the tumor can complicate treatment, and further research is needed to evaluate the effectiveness of postoperative adjuvant therapy and develop therapeutic approaches for recurrent NETs.