The examining physical therapist is assessing a patient with…

The examining physical therapist is assessing a patient with low back pain. The 55-year-old male patient reports his pain as tearing, constant, and throbbing in the lumbar spine. The patient’s medical history includes smoking, hypertension, obesity, and hypercholesterolemia. An extensive examination performed by the PT was not able to reproduce his symptoms in the low back.  What differentia diagnosis should the PT be most suspicious of?