INTRODUCTION
Alkaptonuria is an autosomal recessive disease caused by a deficiency of
homogentisic acid 1,2-dioxygenase that leads to homogentisic acid (HGA)
accumulation. Its clinical signs include dark urine, melanin-like
pigmentation of tissues (ochronosis), and ochronotic arthropathies. HGA
accumulation also affects the cardiovascular system, especially the
heart valves. Alkaptonuria cannot be diagnosed preoperatively since most
of the clinical signs are confirmed intraoperatively.
We present a rare case of aortic valve stenosis (AS) with black
pigmentation caused by alkaptonuria that was diagnosed postoperatively.
Cardiac surgeons should recognize this condition when they observe
typical signs during surgery.