Sciatica caused by pseudomyxoma peritonei

Many etiologies may cause sciatica, and intra-abdominal masses usually affect the lumbosacral plexus by local invasion or distal metastases. Lumbosacral plexopathy caused by compression of intra-abdominal tumors instead of invasion is rarely seen. A 67-year-old woman had a 3-month history of progressive neurogenic claudication, lumbago and left L5 radiculopathy with foot drop. Nocturia and progressive abdominal distension with voiding dysfunction were also noted. Imaging studies showed a huge pelvic mass with severe compression of the left lumbosacral trunk. There was no direct invasion of the lumbosacral plexus by the pelvic mass noted in the preoperative imaging studies or intraoperative findings. Bilateral ovarian borderline mucinous cystic tumor with pseudomyxoma peritonei (PMP) was diagnosed, and the sciatica was improved dramatically after subsequent abdominal debulking surgery. Although rare, neural compression caused by PMP and intra-abdominal masses needs to be considered in the differential diagnosis of sciatica.