Small-bowel gastrointestinal neuroectodermal tumor: a diagnostic challenge at contrast-enhanced ultrasound

Malignant gastrointestinal neuroectodermal tumor (GNET) is an exceptionally rare and aggressive neoplasm. We report the multiparametric ultrasound findings of an ileal GNET in a 38-year-old woman presenting with abdominal pain, vomiting, and weight loss. Baseline ultrasound identified a 4.9-cm pseudokidney-like ileal lesion with circumferential asymmetric wall thickening, partial preservation of wall stratification, and marked parietal vascularity. Dynamic contrast-enhanced ultrasound showed arterial enhancement at 13 s, homogeneous hyperenhancement at 18 s, early wash-out at 36 s, and more pronounced wash-out at 50 s. Ultrasound also detected small liver lesions and guided tissue sampling. Histopathological, immunohistochemical, and molecular analyses, including EWSR1 rearrangement, established the diagnosis. Although the CEUS pattern was not disease-specific, multiparametric ultrasound contributed to lesion localization, vascular characterization, staging, and biopsy guidance.