Objective   To analyze the clinical features, diagnosis, and treatment of primary pelvic retroperitoneal tumors (PPRT).

  Methods   The clinicopathological data of 31 patients with PPRT treated at Tianjin Medical University Cancer Institute & Hospital from October 2000 to May 2021 were retrospectively analyzed.

  Results   Preoperative magnetic resonance imaging (MRI) or computed tomography (CT) examination was performed in all patients. The results revealed that seven patients had retroperitoneal tumors. An ultrasound guided puncture was used to diagnose one patient before surgery owing to the large volume and abundance of blood vessels. All patients underwent surgical treatment, of whom 15 had benign tumors and 16 had malignant ones. Teratoma (5/15) and schwannoma (3/15) were the most common benign tumors, all of which were completely resectable. Sarcoma (9/16) was the most common malignancy, with complete resection in 11 cases and palliative resection in 5. The tumors originating from the fetal residual tissue were located in the median region and were mostly benign and cystic. Conversely, those originating from the mesenchymal and nerve tissues were mainly located in the lateral region and predominantly had solid components. The average patient ages for benign and malignant tumors were 42.1 and 49.7 years, respectively. During the follow-up period, 14 out of the 15 cases of benign tumors showed no recurrence; one case underwent complete resection after recurrence. Of the 16 patients with malignant tumors, 4 were lost to follow-up, 4 died of the disease, 2 had double recurrences (both underwent surgery), and 6 had no recurrence.

  Conclusions   Diagnosing PPRT is challenging, necessitating a comprehensive approach integrating clinical features, gynecological examination, and imaging for accurate differential diagnosis. Ultrasound-guided biopsy of the tumor facilitates the formulation of preoperative treatment, and complete surgical resection is the preferred treatment choice for this disease.