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Pigmented Conjunctival Lesions as Initial Manifestation of Ochronosis
Arch Ophthalmol. 2004;122:1060-1063.
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Alkaptonuria (ochronosis) is an inherited aminoacidopathy of the phenylalanine/tyrosine metabolism (Figure 1). Phenylalanine is an essential amino acid that is irreversibly hydroxylated to tyrosine by homogentisic acid (HGA) oxidase, which is found in the liver and kidneys. In alkaptonuria, the enzyme is absent, and HGA accumulates in collagenous tissues such as cartilage and tendon, especially in the ear, nose, cheeks, conjunctiva, cornea, and sclera. Although conjunctival involvement in ochronosis is rare, it should be considered in the differential diagnosis of pigmented lesions and deposits of the ocular surface. Often, ocular pigmentation is the initial manifestation of the disease.
Figure appears in full text version.
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Figure 1. Graphic representation of the metabolic cascade of phenylalanine in normal and alkaptonuric conditions. The deficiency of homogentisic acid oxidase causes accumulation of homogentisic acid in the involved tissues.
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We report a case of bilateral conjunctival pigmentation as the initial manifestation of alkaptonuria and review the literature on ocular . . . [Full Text of this Article] Report of a Case
Comment
Patricia Chévez Barrios, MD;
Ramon L. Font, MD
Correspondence: Dr Chévez Barrios, Department of Pathology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030 (pchevez@bcm.tmc.edu).
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