PMC8147890_01
(A) MRI images taken 04 Jan 2020 showing mass near right acetabulum. (B) MRI images take 01 Jun 2020 showing a heterogeneously enhancing mass arising from the right acetabulum, extending into the right hip joint.
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It demonstrated a heterogeneously enhancing mass arising from the right acetabulum, extending into the right hip joint (Figure 2B). Compared to the earlier MRI of 4 January 2020 (Figure 2A), this mass demonstrated interval increase in size.
(A) Recurrent pelvic mass with fish-flesh nodules in myxoid lipomatous background. (B) Pelvic mass spindle cell sarcoma. (C) Low-grade sarcoma with pericellular fat infiltration growth pattern typical of DFSP.
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The gross anatomical findings include a recurrent dominant pelvic mass, spatially nearest to the primary groin tumor, that consisted of fish-flesh-like nodules set in a fibromyxoid lipomatous tumor-like mass (Figure 3). The peritoneal lesions comprised small nodules and plaques with rather similar composition. The pelvic mass fish-flesh-like nodules comprised spindle cell sarcoma with a lipomatous background and low-grade, atypical lipomatous patterns (Figure 3A). The colonic peritoneal nodules comprised variegated tumor with circumscribed nodule and infiltrating areas of spindle cell sarcoma and sclerosing lipomatous tumor (Figure 3B). Such morphology in a retroperitoneal sarcoma would be fitting of well-differentiated liposarcoma, sclerosing lipoma-like, with areas of de-differentiated liposarcoma with high-grade spindle cell sarcoma and low-grade dermatofibrosarcoma (DFSP)-like patterns with pericellular fat infiltration (Figure 3C).