Not all acute lower back pain is benign--paravertebral abscess and colonic cancer.

Low back pain with sciatica is one of the most common complaints of patients presenting to the ED, and it is usually managed on an outpatient basis. However, acute lower back pain not always derives from a benign cause. We report here the case of a 63-year-old diabetic man who presented to the ED complaining of acute low back pain with sciatica and fever. The cause was a large paravertebral abscess by Streptococcus milleri, and this was the first presenting sign of an unknown underlying colonic cancer.