Neoplastic lumbosacral radiculoplexopathy in prostate cancer by direct perineural spread: an unusual entity.

Neoplastic lumbosacral plexopathy occurs with some abdominal and pelvic malignancies. Patients present with severe pain radiating from the low back down to the lower extremities, and this progresses to weakness. Neoplastic lumbosacral plexopathy is virtually always associated with known malignancy or obvious pelvic metastatic disease. Uncommonly, prostate cancer can present as a lumbosacral plexopathy occurring through direct pelvic spread. We describe two cases of lumbosacral radiculoplexopathy from infiltrative prostate cancer without evidence of other pelvic or extraprostatic spread. The probable etiology of tumor spreading along prostatic nerves into the lumbosacral plexus (i.e., perineural spread) is discussed as are the potential mechanisms for this unusual mode of cancer dissemination.