[Oculo-cutaneous tyrosinosis (Richner-Hanhart syndrome). Histo-pathological study of a case]

The Richner-Hanhart syndrome corresponds to a tyrosine elevation in serum due to deficit in soluble tyrosine aminotransferase in liver cells. This new enzymopathy which is transmitted in an autosomal recessive mode is called oculocutaneous tyrosinosis. It is curable by a poor diet in tyrosine and its precursors. The diagnosis has been invoked in a 18 months old girl, on the association of punctuate palmar and plantar keratosis, dentritic ulcerated keratitis, and mental retardation. The diagnosis is confirmed by elevation of tyrosinemia to 52 mgs/100 mls associated with a high urinary elimination of tyrosine and plenylcetonic acid. Absences of anomaly in the metabolism of methionin and hepatorenal absence of disturbance of hepatorenal system is characteristic. The keratosis accompany orthokeratotic hyperkeratosis. The keratinocytes show 2 types of anomaly ranged in strates in the epiderm. Intracytoplasmic vacuoles which include or lead to pseudomyelinic formations extend progressively from the mitochondrial alterations in the epidemial basal layers. Bulky polyhedral electron dense particles are found in the cytoplasm of the superficial keratinocytes. Most of these aspects have been demonstrated anteriorly in the keratinocytes and the cornea; on the other hand, signs of mitochondrial sulferance had not been observed. The genesis of these cellular alterations based on the liberation of lysosomial enzymes by the action of crystals of tyrosine has been suggested by Goldsmith from experimental facts. However, it seems the mitochondrial defect occurs outside this mechanism.