Ochronosis is a dermatological disorder that results in the adverse pigmentation of cartilage from a long term buildup of phenylalanine or tyrosine. more...
In this disorder, a pigment substance resulting from incomplete catabolism of tyrosine and phenylalanine is deposited, over the years, in cartilage, the eye, and to a lesser degree in the skin.
Pigmented cartilage may appear blue due to scattering phenomenon, and to a lesser degree this may be true for skin with dermal deposition of this pigment. The skin of the axilla is very likely to be pigmented due to deposits of homogentisic acid in sudoriferous glands in these areas. The clinical features of this metabolic disorder are dark urine, pigmentation of the skin and arthritis. Particularly helpful is the almost constant presence of a patch of pigmentation (gray to brown in color) in the sclera, between the margin of the cornea and the outer or inner canthus. Because of the bluish color produced by the deep pigmentation, this condition may be confused with argyria.
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