Dedifferentiated Liposarcoma of the Epididymis: A Rare Case Report and Analysis

Fig. (1). Pelvic Enhanced MRI. Axial and coronal contrast-enhanced T1-weighted images demonstrate a markedly enhancing lesion in the left epididymal region, indicated by black arrows (a and b). In the coronal view, the spermatic cord indicated by the white arrow demonstrates compression with ill-defined margins and enhancement (a). Axial fat-suppressed T2-weighted image shows a lesion with an isointense signal accompanied by an internal heterogeneous signal (c). Diffusion-weighted imaging (DWI) sequence exhibits significant restricted diffusion within the lesion (d).

Fig. (2). Hematoxylin and Eosin (H&E) Staining and Immunohistochemistry. Under a high-magnification H&E-stained section (×100) microscope, the tumor cells are observed to exhibit a fibrosarcoma-like morphology. The tumor cells (green arrows) are arranged in bundles, with a disordered and irregular cell arrangement. The cells show prominent atypia. Some tumor cells have distinct nucleoli. Individual lipoblasts (red arrows) and numerous tumor giant cells (blue arrows) are visible. Some nuclei are arranged in a wreath-like pattern. Focal hyaline degeneration is seen in part of the tumor stroma, with a small amount of lymphocyte infiltration in focal areas, and obvious blood vessels are present in the stroma(a and b). The results of immunohistochemical staining for CDK4 (c) and MDM2 (d) [both ×100] show that the nuclei of spindle-shaped tumor cells are stained brown, indicating positive expression, suggesting a possible lipogenic tumor. Most of the tumor cells are dedifferentiated components(c and d). Considering the diffuse positive expression of P16 and Desmin, the diagnosis is supposed to be a dedifferentiated liposarcoma.