Abstract
Alkaptonuria is a rare metabolic disease caused by deficiency of homogentisic acid
oxidase and characterized by bluish-black discoloration of cartilages and skin (ochronosis).
Defective production of this enzyme results in the accumulation of homogentisic acid
(HGA), a tyrosine degradation product, in the bloodstream. Accumulation of HGA and
its metabolites in tissues causes ochronosis. The word ochronosis refers to the dark bluish-black discoloration of connective tissues including the
sclera, cornea, auricular cartilage, heart valves, articular cartilage, tendons, and
ligaments. Neurogenic claudication resulting from focal hypertrophy of the ligamentum
flavum in the lumbar spine due to ochronotic deposits has only been previously reported
once in the literature. In this article, we present a 71-year-old male patient with
alkaptonuria-associated degenerative L3–L4–L5 stenosis, diagnosed after lumbar decompressive
laminectomy.
Keywords
black colored - ligamentum flavum - alkaptonuria
