case_images: PMC10481824_01
case_images: An 86-year-old male with cystic retroperitoneal dedifferentiated liposarcoma who presented with unexplained weight loss and frequent falls. Axial (a), Coronal (b), and Sagittal (c) contrast enhanced computed tomography (CT) images of the abdomen and pelvis in the portal phase demonstrate a large heterogenous complex cystic lesion in the left retroperitoneum (arrows). Differential considerations on CT included a complex hematoma, abscess, or a cystic tumor.
case_images: JCIS-13-22-g001.jpg
case_images: PMC10481824_01_JCIS-13-22-g001.jpg
case_images: F1
case_images: A contrast-enhanced computed tomography (CT) scan of the abdomen and pelvis was obtained which showed a large heterogeneous complex cystic hypoenhancing lesion in the left retroperitoneum posterior to the left kidney measuring 13 x 12 x 24 cm and demonstrating mixed density of 9-32 Hounsfield units [Figure 1].
case_images: An 86-year-old male with cystic retroperitoneal dedifferentiated liposarcoma who presented with unexplained weight loss and frequent falls. Axial T2 (a), Axial T1 (b), Coronal T2 (c), and Coronal fatsaturated T1 (d) Images demonstrate heterogeneous mixed T2 signal intensity with foci of T2 high signal intensity throughout the lesion consistent with cystic components (white arrows). Multiple areas of T1 high signal suggesting hemorrhage of different ages (red arrows).
case_images: JCIS-13-22-g002.jpg
case_images: PMC10481824_01_JCIS-13-22-g002.jpg
case_images: F2
case_images: Subsequent magnetic resonance imaging (MRI) demonstrates heterogeneous T2-weighted hyperintensity suggestive of multi-cystic areas within the mass [Figure 2]. Multiple areas of T1-weighted hyperintensity are also seen on the T1 fat saturated sequence suggestive of hemorrhagic content [Figure 2].
case_images: An 86-year-old male with cystic retroperitoneal dedifferentiated liposarcoma who presented with unexplained weight loss and frequent falls. T1 in-phase (a) and T1 out-of-phase (b) images as well as diffusion-weighted imaging (c) and apparent diffusion coefficient map (d) demonstrate foci of microscopic fat in the superior portion of the retroperitoneal mixed cystic mass (white arrow), and restricted diffusion in the periphery of the retroperitoneal heterogenous mixed cystic mass (red arrows).
case_images: JCIS-13-22-g003.jpg
case_images: PMC10481824_01_JCIS-13-22-g003.jpg
case_images: F3
case_images: T1 imaging [Figure 3] demonstrates associated microscopic lipid content as denoted by signal loss on the out-of-phase image compared to the in-phase image in the superior cystic component of the mass [Figures 3a and 3b]. There is diffusion restriction in the periphery of the solid components of the mass [Figure 3d]. The solid components show avid enhancement in the post-contrast fat saturated T1 [Figure 4]. Given the signal loss seen on the out-of-phase image [Figure 3b arrow], the first differential diagnosis considered is liposarcoma, followed by lymphoma or peripheral nerve sheath tumor.
case_images: An 86-year-old male with cystic retroperitoneal dedifferentiated liposarcoma who presented with unexplained weight loss and frequent falls. Post contrast axial fat saturated T1 (a) and subtraction (b) as well as post contrast coronal fat saturated T1 (c) and subtraction (d) images demonstrate enhancement of the thick irregular peripheral walls of the mass and its thick internal septations (white arrows). No enhancement of the predominantly central cystic components (asterisk).
case_images: JCIS-13-22-g004.jpg
case_images: PMC10481824_01_JCIS-13-22-g004.jpg
case_images: F4
case_images: There is diffusion restriction in the periphery of the solid components of the mass [Figure 3d]. The solid components show avid enhancement in the post-contrast fat saturated T1 [Figure 4].