Ochronosis ,The Rare Cause of Chronic Low Back Pain: Report of A Case

Background and Importance: 

Alkaptonuria is a rare genetic disorder due to deficiency of the enzyme homogentisic acid Oxidase which results in the accumulation of homogentisic acid in various body tissues; it produces a multisystemic disorder with a characteristic bluish-black discoloration of the skin and cartilage, termed ochronosis.

Herein, we reported A 45-year-old female patient presented to our outpatient clinic with chronic low back and left leg radiated pain that aggravated gradually in the previous six months. She also suffered from progressive muscle weakness in her left lower extremity. The patient was operated for prolapsed disc herniation. Macroscopically, no abnormality of the skin, muscles or ligaments was observed during surgery. After the annulus was incised, surprisingly it was seen that the nucleus pulposus removed from the L3-L4 disc space was black. The alkaptonuria was diagnosed after histopathological examination of the black disc material and also was confirmed by urinalysis.

The postoperative course was uneventful and the patient was free from low back and leg pain after surgery. In patients with no other signs of alkaptonuria or ochronosis such as our case, early detection of this rare disease is important to asses and treat the involvement of other systems (e.g., cardiovascular and urinary).