Aggressive Orbital Dedifferentiated Liposarcoma With Osseus Components in a Young Woman.

Background/Aim: Dedifferentiated liposarcoma (DDLS) is a rare but aggressive subtype of liposarcoma that arises in soft tissues. In orbital liposarcoma, malignant transformation from well-differentiated to DDLS typically takes at least a year. We herein report a case of a young female with an aggressive DDLS, that developed from an orbital lipoma within one year. Case Report: A 25-year-old woman presented with left upper eyelid swelling. MRI revealed abnormal adipose tissue in the medial orbit. The excised tissue was diagnosed as an orbital lipoma. The eyelid swelling recurred three months later, and the orbital tumor enlarged. An additional resection was performed, which again revealed a lipoma without malignant features. Three months later, the swelling worsened, and tumor resection confirmed well differentiated liposarcoma with a Ki-67 labeling index of 10%. Two months later, CT imaging depicted calcified lesions within the tumor. The patient subsequently underwent orbital exenteration followed by proton beam radiation. Histopathological examination of the exenterated tissue revealed DDLS with extensive osseous components. The Ki-67 labeling index exceeded 50%. Conclusion: Ocular oncologists should pay attention to the possibility of rapid malignant transformation in DDLS in primary orbital liposarcoma.