LAUSR

Tyrosinemia type II (OMIM #276600), also called RichnerHanhart Syndrome (RHS), is a rare autosomal recessive metabolic disease caused by a deficiency of the cytosolic enzyme tyrosine aminotransferase (TAT) (1). It can be detected in neonatal screening, but newborns are not routinely tested due to rarity of the disease (2). Deficiency of TAT enzyme leads to increased serum tyrosine, causing cutaneous, ocular and neurological changes (3). Neurological manifestations include intellectual disability, convulsions, tremor, ataxia and nystagmus (4). The main cutaneous manifestation is painful palmoplantar hyperkeratosis (3). Corneal pseudodendritic keratopathy can be found as early as in the first months of life (5) and is often misdiagnosed as herpetic keratitis (3). It is possible that episodes of spontaneous remission/exacerbation of pseudodendrites occur, simulating a coincidental clinical response to empiric antiviral therapy, even in the absence of typical skin lesions (6). Intra-cellular deposition of tyrosine crystals can lead to an inflammatory tissue response and is probably responsible for damage to the eyes and skin (5). Treatment of these patients consists of a diet restricted to tyrosine and phenylalanine as early as possible, so as to warrant normal cognitive development (6). We report a patient who presented with pseudodendritic keratopathy simulating herpetic keratitis as the initial manifestation of RHS.