Introduction
Ochronosis is a rare condition caused by the accumulation of homogentisic acid in the connective tissues throughout the body. This accumulation results in the discoloration of tissues to a blue-yellow hue. This can be seen in the sclera of the eyes1, nails2, bones3, skin2-5, thyroid gland6, substantia niagra6, coronary arteries6 and cardiac valves6. This discoloration makes for interesting physical examination findings. The associated differential diagnosis is quite narrow. Causes of ochronosis are either exogenous or endogenous. Those that are exogenous include chemical exposure or ingestion, whereas endogenous causes include inborn errors of metabolism.