Alkaptonuric Ochronosis.

Alkaptonuria is a rare autosomal recessive disorder of tyrosine metabolism. Deficiency of homogentisate 1,2 dioxygenase results in accumulation of oxidized homogentisic acid in the connective tissues of the skin, eyes and ears, musculoskeletal system, and cardiac valves, and in urolithiasis. Excretion of excessive homogentisic acid in urine causes dark-colored urine on exposure to air. We present a case of alkaptonuria with multiple system involvement, who presented with lower urinary tract symptoms secondary to vesical and prostatic calculi.