Postoperative Lumbar Plexopathy Secondary to Retroperitoneal Liposarcoma: A Case Report

Liposarcoma is a rare malignancy that usually originates in the extremities or the retroperitoneum. The lumbar plexus, a complex neural network formed by divisions of the first four lumbar roots, penetrates the psoas muscle before it exits the pelvis. Owing to their anatomical proximity, neoplasms in the vicinity of the psoas muscle may involve the lumbar plexus. We report a case of postoperative lumbar plexopathy involving the posterior divisions of the lumbar plexus, following the resection of a recurrent retroperitoneal liposarcoma located in the dorsal aspect of the psoas muscle. A 50-year-old man visited a rehabilitation clinic for an evaluation of proximal weakness of the unilateral lower extremity after resection of a recurrent liposarcoma of the left psoas muscle. Physical examination showed weakness of left hip flexion and knee extension accompanied by sensory loss in the left anteromedial thigh and the medial lower leg. An electrophysiological study revealed left lumbar plexopathy with selective involvement of the posterior divisions of the lumbar plexus. The patient could walk independently without a walking aid on level surfaces while he underwent exercise therapy. A comprehensive evaluation, including a physical examination, the use of imaging modalities such as computed tomography for anatomical characterization, and electrophysiological studies, is important for accurate diagnosis.