Prenatal ultrasound diagnosis, intrauterine monitoring and postnatal management of a giant fetal abdominopelvic lymphangioma: a case report and scoping review.

Background: Fetal lymphangioma is a rare congenital malformation, generally isolated and clinically asymptomatic, except when it invades adjacent tissues, causing compression-related symptoms. Objectives: To present a rare case of a giant fetal abdominopelvic lymphangioma and to perform, to our knowledge, the first scoping review of the literature specifically addressing prenatal diagnosis, intrauterine monitoring and postnatal management of this condition. Methods: The PubMed, Scopus and Embase databases were searched up to September 2025. No limitations on the country were made. Results: We present the case of a 38-year-old primigravida with gestational diabetes, hypothyroidism and severe obesity referred to our institute for a second opinion after prenatal detection of a large multiloculated cystic abdominal mass in the fetus, extending to the pelvis, without vascularization. Follow-up imaging, including a fetal magnetic resonance imaging (MRI), confirmed the suspicion of a giant lymphatic malformation with progressive fetal ascites and associated symptomatic polyhydramnios requiring amnioreduction. A male infant was delivered via emergency cesarean section at 34 + 3 weeks and admitted to neonatal intensive care unit (NICU) with respiratory distress. Due to progressive clinical worsening and persistent fluid accumulation, an abdominal drain was placed, followed by debulking surgery at four months, which confirmed the diagnosis of lymphangioma. Gradual clinical improvement enabled the patient's transfer to the Nutritional Rehabilitation Unit and subsequent discharge. Regarding the scoping review, 20 case reports fulfilled the inclusion criteria. Patients were analyzed concerning the prenatal ultrasound diagnosis of a fetal abdominal lymphangioma, pregnancy outcomes, intrauterine and postnatal treatment of the mass. Conclusion: Clinical presentation and outcomes of fetal abdominal and abdominopelvic lymphangiomas are highly heterogeneous and strongly influenced by lesion extent and intra-abdominal involvement. Our case, characterized by diffuse intestinal and mesenteric disease, highlights the limitations of curative surgical strategies and underscores the need for early recognition of patients who may require prolonged supportive management rather than a complete excision. The scoping review suggests that while focal lesions are often amenable to surgery with favorable outcomes, diffuse forms often require a multidisciplinary, staged approach, with realistic prognostic counseling and long-term follow-up.