1. ANTENATAL DIAGNOSIS OF AN ABDOMINAL MASS: WHAT CAN WE EVOKE? N.Sghairoun*, S.Sahli*, A.BenSlama*, S.Blibech**, M.Gasmi*, M.Douagi**, M.Hamzaoui*. * : Department of pediatric surgery « A », Children Hospital, Place Bab Saadoun, 1007, Tunis, Tunisia. ** : Department of neonatology,MPIT, Tunisia. INTRODUCTION The considerable progress realized by the imaging has modified the forecast of the neonatal tumors. If the topographic of such tumors still raise various problems in fetal period, it remains however easy to understand all the advantages of the antenatal diagnosis. Herein, the authors report a case of fetal abdominal mass and discuss the diagnosis and therapeutic management. CASE REPORT A16 days new born was admitted for intra abdominal cystic mass diagnosed in 26 weeks of pregnancy. Physical examination revealed hypertension and voluminous right sided mass, exceeding the median line, coming down to the pubis, firm, painless and urinary infection. Imaging showed a retroperitoneal mass measuring 100 mm x 90 mm with cystic and tissular components, repulsing the right kidney below and outside, seeming to develop from the right surrenalian gland (figure 1). Catecholamins were negative with anaemia (6 gramms by deciliter) and renal insufficiency. Retrograde cystography lead to a IV staged vesicoureteral left reflux (figure 2) The patient underwent surgery after renal disorders correction (decrease of uree from 565 to 295 micromoles by millileter) and stabilisation of the blood pressure. Laparotomy discovered a retroperitoneal tumor (figure 3) independing of the voluminous right kidney wich was flattened, its pedicule compressed and its ureter fine. The surrenalian gland and the liver were normal. The mass has been totally removed. The boy was discharged to the neonatology department within 6 days. The histological study confirms the diagnose of an immature teratoma rank 3 according to the world health organization. The follow-up was uneventful. The passing is for 6 months with normal renal fonction. CONCLUSION Despite progress in imaging,etiologic and topographic diagnosis of retroperitoneal mass discovered antenatally remains problematic before surgery. DISCUSSION The aim of imaging in abdominal mass in fetus or neonate is to determinate the topography (intra or retroperitoneal), organ of origin, character (cystic/solid/mixed), measurement, effect on contiguous organs and eventually the presence of metastasis. This is not always as easy as expected, especially when the mass is very large. The most frequent abdominal neoplasms occurring during infancy and causing raised blood pressure are depending on the sympathetic nervous system, either adrenal or extraadrenal. Neuroblastoma occur in the neonate as a congenital neoplasm but it is generally diagnosed after 6 months. Wilms’ tumor represents the second etiology but it remains uncommon Retroperitoneal teratoma (RPT) is a rare in newborns. Recent reports in the literature contain small numbers. Luo reported 10 patients who underwent excision of this tumor at a single institution over a 5-year period. As well as our experience, they found surgical excision easy. This is explained by the lack of adherence of the tumors to the retroperitoneal organs except by areolar tissue, called “unattached retroperitoneal tumors”. Follow-up must be regular and prolonged to screen recurrences. Figure 1: retroperitoneal mass measuring 100 mm x 90 mm with cystic and tissular components, repulsing the right kidney below and outside, seeming to develop from the right surrenalian gland Figure2: Retrograde cystography lead to a IV staged vesicoureteral left reflux Figure3: Specimen