UNDIFFERENTIATED (EMBRYONAL) SARCOMA OF THE LIVER - PATHOLOGICAL BASIS OF IMAGING FINDINGS IN 28 CASES

PURPOSE: To correlate the imaging and pathologic features of undiffere ntiated (embryonal) sarcoma (UES) and account for the discrepancy betw een the solid appearance at ultrasound (US) and the almost cystlike ap pearance at computed tomography (CT) and magnetic resonance (MR) imagi ng. MATERIALS AND METHODS: The clinical, pathologic, and imaging findi ngs in 28 patients (age range, 3-49 years) with pathologically proved UES were retrospectively reviewed. All patients underwent at least one cross-sectional imaging study to include CT (27 patients), US (21 pat ients), and MR imaging (six patients). Tumor size, gross morphology (n = 27), histologic features, and proportion of solid and cystlike comp onents were evaluated and correlated to the imaging findings. RESULTS: The mean transverse diameter of the tumors was 14 cm (range, 10-25 cm ). At gross examination, the tumors were predominantly solid (mean, 83 % of tumor volume), and pathologic and US findings were concordant. Co nversely, CT scans showed low attenuation (approximately that of water ) in 88% of the tumor volume and T2-weighted MR images showed high sig nal intensity (approximately equal to that of cerebrospinal fluid) in 89% of the tumor volume. CONCLUSION: UES shows a misleading cystlike a ppearance at CT and MR imaging compared with US and pathologic finding s. In a child or young adult with a liver tumor, this finding is usefu l in making a prospective diagnosis and avoiding misguided attempts at drainage.