RESUMO
Alkaptonuria, is a rare metabolic autosomal recessive disorder, which affects 1:1,000,000 people. It is also called endogenous ochronosis. Though it is mainly seen in children, in adults it usually presents after the age of 30.1 It arises from decreased activity of liver homogentisate 1,2-dioxygenase which leads to accumulation of homogentisic acid (HGA) and production of a melanin-like polymer which is deposited mainly in cartilaginous tissue, mucous, skin, bone surface, internal cardiac structures, as well as excreted in urine.2 The main presentation of alkaptonuria is valvular calcifications and osteoarthritis of spine, along with dark pigmentation of skin, cartilage, sclera and other connective tissues. It is diagnosed by a combination of clinical history, histopathological examination, and estimating the levels of homogentisic acid in urine.3