Richner-Hanhart syndrome (tyrosinemia type II): a case report of delayed diagnosis with pseudodendritic corneal lesion

Richner-Hanhart syndrome (tyrosinemia type II) is a rare autosomal recessive disease associated with high serum tyrosine levels caused by the deficiency of tyrosine aminotransferase enzyme. We report a 15-year-old female patient with complaints of bilateral photophobia and tearing, which started during the infancy period. Biomicroscopic examination revealed bilateral circular corneal opacities on the inferior quadrant and small dendritic lesions at the center of the circular opacities. Blood tests showed a tyrosine level of 508 micromol/L (normal range: 30-150). On her dermatologic examination, plantar hyperkeratosis and seborrheic dermatitis were noted, and mild mental retardation was detected. One and a half months after the tyrosine- and phenylalanine-restricted diet, her tyrosine level dropped to 395 micromol/L level, her corneal lesions subsided, and a symptomatic relief was achieved. Tyrosinemia type II should be suspected in patients demonstrating dermatologic signs, especially palmoplantar keratosis, associated with bilateral pseudodendritic corneal lesions unresponsive to antiviral therapy.