Introduction/Background Retroperitoneal tumours are rare tumours, which could be defined as cystic or solid masses in imagistic investigations and could be divided in benign or malignant tumours. More than 70% of the primary retroperitoneal masses are malignant. The most common in this region are sarcomas. Also epithelial malignancies, lymphomas and metastases of different germ cell tumours may appear in the retroperitoneum. From the benign lesions most frequent are lipomas, fibromas and benign neurogenic tumours. During pregnancy, both benign and malignant retroperitoneal tumours are extremely rare.

Results We present the case of a 34 years old VIIIG VIIP pregnant patient, recently admitted to our hospital for uterine contractions. The ultrasound examination diagnosed a gigantic abdominal mass and a 20 weeks pregnancy with an anencephalic fetus. After counselling the patient, the medical abortion was induced. CT was performed after and so we had the imaging of 20/15/13 cm tumour with a mixed, incapsulated structure, predominantly liquid, with parenchymal areas inside, heterogeneously iodophilic, with focal calcifications and a regular outline. The tumor develops from the left intersplenorenal space and occupies the entire left half of the abdomen. For our patient the surgery was recommended, but she refused it, because the symptoms were minor, excepting the deformation of the anterior abdominal wall.

Conclusion Contrast-enhanced computed tomography (CT) and MRI are the most important in diagnosing this type of tumours, but the differential diagnosis of these masses in retroperitoneum - malignant or benign, is done by histopathology. Usually, no symptoms appear until retroperitoneal tumours reach an important volume, so they are incidental diagnosed during investigations for nonspecific complaints. First step of treatment is surgery with complete tumour resection followed by anatomopathology and the management will be choose for the best prognosis of the patient.

Disclosures I do not have any conflict of interest with any person or organization.