PMC9403054_01
Axial CT (A-C) and fused PET/CT (D-F) images showed retroperitoneum mass with unevenly mildly increased metabolic uptake (A,D) and mixed lytic and sclerotic changes of left iliac bone (B,E) and L5 (C,F). Adjacent bones also presented mildly increased metabolic uptake.
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F1
The boundary of the lesion is not clear, with an approximate size of 3.3 cm x 2.5 cm and SUVmax of 1.7 (Figures 1A,D). L5, and left iliac bone showed mixed lytic and sclerotic changes, SUVmax of 1.8 (Figures 1B,C,E,F). Left psoas, iliopsoas, erector spinae, and gluteus medius were enlarged when compared to contralateral side muscles, as also evident at a subsequent contrast-enhanced
Contrast-enhanced CT scan, coronal view (A), and axial view (B), showed the ill-defined lesion of the retroperitoneum (A) (red arrow) and rich blood vessels (B) (yellow arrow) in the mass.
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F2
CT scan. Contrast-enhanced CT scan showed the ill-defined lesion (Figure 2A) and rich blood vessels in the mass (Figure 2B).
Photomicrograph showed irregular spindle tumor cell nodules in the lesion, containing a large number of red blood cells (A) (HE, original magnification x 10). Higher magnification showed a glomeruloid pattern of small central slit-like vessels (B) (HE, original magnification x 20). Neoplastic cells are positive for CD31 (C) (original magnification x 10), and D2-40 (D) (original magnification x 10).
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F3
Photomicrograph of the specimen showed there are many irregular hemangioma-like tumor cell nodules in the lesion, containing a large number of red blood cells (Figures 3A,B). The tumor cells were positive for Vimentin, CD31 (Figure 3C), CD34, ERG, SMA, and D2-40 (Figure 3D).
Ultrasound image showed a significant decreased (80%) volume of peritoneal mass before (A) and after 6-month Sirolimus monotherapy (B).
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F4
After 6-month sirolimus monotherapy, the retroperitoneal mass was reduced by 80% (Figure 4) and the clinical symptoms almost disappeared.