Half abdomen tumor – giant retroperitoneal lipoma: a case report and review of the literature

Figure 1. Axial (A) and coronal (B) CT scan sections showing a large, circumscribed retroperitoneal tumor, with mass effect on the adjoining organs. The ureter crosses the tumoral tissue right in the middle. CT: Computed tomography

Figure 2. (A and B) 3D CT reconstruction demonstrating the mass effect produced on the left colon, urinary bladder, and the impact on the left ureter, which appears to be deformed in the lumbar segment. 3D: Three-dimensional; CT: Computed tomography

Figure 3. (A and B) MRI sections revealed a massive adipose tumor, which is modifying the local anatomy. Some more dense structures with irregular shapes can be observed in these images. The ureter is crossing the tumor right thru the middle, and the urinary bladder is compressed and deviated from the usual place. MRI: Magnetic resonance imaging

Figure 4. Gross appearance of the whole tumoral tissue demonstrating a yellow, greasy cut surface (A) and a section through one of the suspect nodules (B) described by the radiologists. The pathologists separately examined the nodules having a different consistency

Figure 5. Intraoperative aspect after excising the 6.4 kg giant retroperitoneal mass. The intraperitoneal and retroperitoneal organs were entirely preserved

Figure 6. Microscopic aspects of the lipoma tumor: (A) Adipocytes with variable size separated by conjunctive septa with variable thicknesses; (B) Thick fibrous septa with moderate chronic inflammation; (C) Area of conjunctival septa with nonspecific granulomatous inflammation and vascular congestion; (D) Tumor tissue with a poor vascular network; (E) Tumor tissue with low Ki67 proliferation index. HE staining: (A–C) ×100. Immunolabeling with anti-CD34 antibody: (D) ×100. Immunolabeling with anti-Ki67 antibody: (E) ×100. CD34: Cluster of differentiation 34; HE: Hematoxylin–Eosin

Figure 7. Axial (A) and coronal (B) CT scan sections at 12 months follow up reveals no signs of tumor recurrence. On the 3D reconstruction (C), it can be observed that even though all the organs regained their anatomical positions, the ureter still presents some deformations with normal renal function. 3D: Three-dimensional; CT: Computed tomography