(0600) A Case Report of a 17-Centimeter Retropharyngeal Well-Differentiated Liposarcoma With Bilateral Neck Extension

Introduction: Liposarcomas are rare malignant adipocytic tumors that primarily occur in the lower extremities and retroperitoneum, with a low incidence in the head and neck region. This report details an unusual case of well-differentiated retropharyngeal liposarcoma in an 81-year-old male, highlighting diagnostic challenges and the critical role of MDM2 FISH analysis in pathology confirmation.

Methods: The patient presented with dysphagia attributed to a retropharyngeal mass identified on head computed tomography (CT), not evident in a previous CT 33 months earlier. Diagnostic assessment, including tru-cut biopsy and cytology, revealed atypical nuclear features in adipocytes. MDM2 FISH analysis confirmed the diagnosis, detecting MDM2 gene amplification. Three-dimensional CT reconstruction showed the mass mainly in the left retropharyngeal space with extension to the right neck.

Results: Surgical excision, tailored to tumor size and extension, involved left neck dissection via a hockey stick incision. A subplatysmal flap facilitated mass separation from adjacent structures, ensuring nerve preservation. The retropharyngeal mass was completely excised with no complications. Pathology confirmed a 17 cm well-differentiated liposarcoma with focal involvement of resection margins (pT3, pN0). Neck CT following post-operative radiotherapy yielded no evidence of disease recurrence.

Conclusions: Retropharyngeal liposarcomas pose diagnostic challenges, necessitating MDM2 FISH analysis for pathology confirmation. Early surgical intervention, guided by tumor characteristics, is crucial for optimal outcomes. This case underscores the importance of a meticulous surgical approach in achieving successful outcomes for retropharyngeal liposarcomas.