A rare case of fetal retroperitoneal solid mature teratoma.

article's main point: This article retrospectively analyzes clinical data from a rare case of fetal retroperitoneal solid, mature teratoma, aiming to provide insights into diagnosing and treating fetal teratomas. This case of fetal retroperitoneal teratoma provides the following insights into diagnosis and treatment: 1) Due to the special nature of the retroperitoneal space, retroperitoneal tumours grow hidden, especially in fetal retroperitoneal tumours that are even more difficult to detect. Prenatal ultrasound screening is of great value for the diagnosis of this disease. 2) Although ultrasound can determine the location and blood flow of the tumour and monitor changes in its size and composition, there is a certain degree of misdiagnosis due to fetal position, clinical experience, and imaging resolution. When necessary, fetal MRI can provide further evidence for prenatal diagnosis. 3) Although fetal retroperitoneal teratoma is rare, a few tumours grow rapidly and have the potential for malignant transformation. When a solid cystic mass lesion in the retroperitoneal space is found during the fetal period, this disease should be considered as one of the differential diagnoses and distinguished from fetal renal tumours, adrenal tumours, pancreatic cysts, meconium peritonitis, parasitic fetus, and lymphangioma, among others. 4) Based on the situation of the pregnant woman, fetus, and tumour, the time and method of termination of pregnancy should be decided. After birth, the timing and manner of surgery and postoperative follow-up should be determined by neonatology and pediatric surgery.