ochronosis, the rare cause of herniation of a disc: a case report

Background and importance: alkaptonuria is a rare genetic disorder due to homogentisic acid oxidase deficiency which eventuates in the reposition of homogentisic acid in different parts of the body and multi-organ involvements. the characteristic bluish-black discoloration of the skin and cartilage tissue are known as ochronosis. case presentation: herein, we reported a 45-year-old woman with chronic pain in the lumbar area and radicular pain in her left leg, aggravating gradually during the previous six months before operation. she also suffered from progressive muscle weakness in her left lower extremity. the patient was the operated for prolapsed disc herniation. macroscopically, no abnormality of the skin, muscles, or ligaments was observed during surgery. after incision of the annulus in level l3- l4, surprisingly the excised nucleus pulposus was black. the alkaptonuria was diagnosed after histopathological examination of the black disc material and confirmed by urinalysis. conclusion: the postoperative course was uneventful and the patient was free from low back pain and leg pain after surgery. in patients without any manifestations of alkaptonuria or ochronosis such as our case, timely diagnosis of this pathologic condition is momentous for investigation, treatment, and prevention of other organs’ involvement.