Atypical Radiological Presentation of a Neonatal Primary Retroperitoneal Teratoma Undergoing Haemorrhagic Evolution: A Case Report.

Primary retroperitoneal teratomas are rare extragonadal germ cell tumours that originate from totipotent embryonic cells misplaced during embryogenesis. These tumors are more commonly seen in neonates and infants and may remain asymptomatic until they reach a significant size, leading to compressive symptoms. Here, we present a case of a 15-day-old neonate with progressive abdominal distension since birth and a fever for three days. Prenatal ultrasonographic imaging at 22-23 weeks gestation detected an intra-abdominal cystic lesion, initially suspected to be a duplication or mesenteric cyst. By 29-30 weeks, the lesion showed solid components with possible calcifications, raising suspicion of an intra-abdominal teratoma. Through detailed clinical evaluation, radiographic imaging, and diagnostic modalities, including chest radiography, ultrasound, computed tomography and magnetic resonance imaging, the anatomical features and associated complications were delineated. Surgical excision was performed, and histopathological examination revealed haemorrhagic infarction of a teratoma, confirming the diagnosis. Primary retroperitoneal teratomas in neonates are uncommon and may mimic other congenital cystic or solid abdominal masses. This case underscores the importance of early detection and multidisciplinary management in optimizing outcomes.