BACKGROUND: Retroperitoneal liposarcoma is a malignant soft tissue sarcoma arising from adipocyte precursors, with an incidence of 3-4 cases per million. Giant retroperitoneal tumors pose significant surgical challenges due to their size and proximity to vital structures.

CASE REPORT: We report the case of a 61-year-old woman who presented with progressive abdominal distension, mild discomfort, nausea, dyspepsia, and exertional dyspnea. Preoperative MRI revealed a giant retroperitoneal mass (28×23.6×24 cm) with heterogeneous adipose and non-lipomatous components, initially suggestive of dedifferentiated liposarcoma. However, ultrasound-guided core needle biopsy revealed histopathological findings consistent with well-differentiated liposarcoma (WDLPS). Complete surgical excision via midline laparotomy was performed; the tumor weighed 10 kg. Despite the massive tumor size, complete tumor removal was achieved while preserving adjacent organs, without the need for multivisceral resection. Histopathological examination was consistent with WDLPS with negative margins (R0), no vascular invasion (V0); staged pT4. Postoperative MRI, whole-body scintigraphy, and PET/CT showed no residual or metastatic disease. No adjuvant therapy was administered, and at 3-month short-term follow-up, there was no evidence of residual or recurrent disease.

CONCLUSIONS: This case suggests the feasibility of complete surgical excision with organ preservation in selected cases of giant retroperitoneal liposarcoma with clear dissection planes. It also underscores the role of preoperative imaging and core needle biopsy in diagnostic evaluation and surgical planning. Surgery remains the standard treatment, while the role of adjuvant therapy depends on histological subtype. Longer follow-up is required to assess long-term oncologic outcomes.

Keywords: Biopsy, Needle, Case Reports, Liposarcoma, Magnetic Resonance Imaging, Retroperitoneal Neoplasms, surgical oncology