PMC8504230_01
MRI images of DDLPS. Axial fat-saturated T2-weighted image (a) and coronal T2-weighted image (b) show a relatively well-defined pure fatty mass (white arrows), surrounding a non-fatty solid mass. DDLPS: dedifferentiated liposarcoma; MRI: magnetic resonance imaging.
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The MRI signal intensity for most of the mass was hyperintense on T1-weighted images and T2-weighted images (Figure 1(a)), with drop-out on MRI fat-suppressed sequence images (Figure 1(b)).
Gross appearance of DDLPS. The cross section of the WDLPS reveals yellow tissue, the high-grade DDLPS is fish flesh-colored, and the middle necrotic area is pale yellow; the low-grade DDLPS (white arrows) is gray-white, but the local area is grayish-brown. DDLPS: dedifferentiated liposarcoma; WDLPS: well-differentiated liposarcoma.
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There was a clear boundary between brown tumor foci near the capsule and other gray-white or fish flesh-colored tumor foci (Figure 2).
Histologic analysis of dedifferentiated liposarcoma specimens. (a) Typical well-differentiated liposarcoma of the adipocytic/lipoma-like type (hematoxylin-eosin stain; x100). (b) High-grade dedifferentiated liposarcoma demonstrates high cellularity, pleomorphism, and marked cellular atypia (hematoxylin-eosin stain; x100). (c) and (d) Transition from low-grade dedifferentiation with inflammatory myofibroblastic tumor-like features to high-grade dedifferentiation with undifferentiated pleomorphic sarcoma features (hematoxylin-eosin stain; c x40). The boundary (white arrows) between them is clear (hematoxylin-eosin stain; d x20). (e) and (f) Transition from low-grade dedifferentiation with fibromatosis-like features to high-grade dedifferentiation with undifferentiated pleomorphic sarcoma features (hematoxylin-eosin stain; ex40). The boundary (white arrows) between them is clear (hematoxylin-eosin stain; f x20).
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Most of the solid nodule were high-grade pleomorphic undifferentiated sarcomas with extensive tumor necrosis, and the tumor cells had obvious atypia and active mitotic images (about 50/50 high-power microscopic field; HPF) (Figure 3(b)). The low-grade DDLPS were located near the capsule of the solid nodule; histologically, they were inflammatory myofibroblastic tumor-like (Figure 3(c)) and fibromatosis-like features. Most of the tumor cells were spindle-shaped and had slight atypia, with pleomorphic tumor cells occasionally seen (Figure 3(e)). The low-grade DDLPS with multiple foci can be seen, which suddenly transits to the high-grade DDLPS (Figure 3(d) and (f)).
Fluorescence in situ hybridization of the MDM2 gene. FISH analysis confirmed MDM2 gene amplification (clustering of red signals) in the nuclei of atypical cells. FISH: fluorescence in situ hybridization.
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Fluorescence in situ hybridization (FISH) analysis showed the presence of MDM2 gene amplification (Figure 4).