Neoplastic Lumbosacral Plexopathy Differential Diagnoses

Updated: Aug 31, 2023
  • Author: Rajesh R Yadav, MD; Chief Editor: Dean H Hommer, MD  more...
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Diagnostic Considerations

These include the following:

  • Other causes of lumbosacral radiculopathy

  • Primary plexus tumors

  • Epidural cord compression

  • Chemotherapy toxicity associated with intra-arterial treatment

  • Diabetic amyotrophy

  • Obstetric procedures

  • Intragluteal injections

Meningeal carcinomatosis or leptomeningeal disease also may cause low back or leg pain with subacute motor or sensory involvement; however, patients with these conditions often demonstrate mental status changes, headaches, cranial nerve palsies, and/or nuchal rigidity.

In cancer patients with thrombocytopenia, retroperitoneal bleeding can cause plexopathy accompanied by a rapid onset of pain and neurologic signs that usually are fully developed in 24 hours. Other associated findings include flank, thigh, or low back ecchymoses. A retroperitoneal bleed usually involves the femoral nerve and occasionally will spread to other parts of the plexus.

Other causes of lumbosacral plexopathy to consider are idiopathic in nature, aortic aneurysms, diabetes mellitus, obstetric procedures, trauma, anticoagulation therapy, retroperitoneal hematomas, surgical intervention for mesenteric thrombosis, kidney transplantation, tuberculosis, and intragluteal injections. [16, 17, 18, 19, 20, 21, 22]

Acute pain is common with aortic aneurysm, and the resultant weakness typically worsens over 1-2 weeks and then stabilizes. A pulsatile rectal or abdominal mass frequently is observed.

Acute thigh pain with acute or insidious onset weakness can result from diabetic amyotrophy and can be difficult to differentiate from the pain associated with an aortic aneurysm. In diabetic amyotrophy, weakness is more often noted proximally, with relative sparing of distal lower extremity muscles.

Differential Diagnoses