Exogenous ochronosis: An overview

Exogenous ochronosis/colloid milium in Blacks is a relatively unknown condition in the USA, but a relatively high incidence has been observed in South Africa. Physicians reporting adverse reactions, observe these effects almost exclusively in the facial areas exposed to sunlight. These effects can be attributed to several causative factors to explain the striking difference in the incidence between the USA and South Africa. Prior to 1984, neither the type nor concentration of skin lightening compounds sold in general commerce in South Africa were regulated. Therefore, it was not uncommon for products to contain 6-8% hydroquinone as opposed to the 2% hydroquinone level utilized in over-the-counter skin discoloration fade creams available in the USA. Secondly, the combination of higher hydroquinone concentrations together with other preparations containing ochronotic agents such as phenol and resorcinol provided the basis for the high incidence of ochronosis (pre-1984) in South Africa. Thirdly, the use of hydroalcoholic lotions in South Africa permitted formulations with higher hydroquinone concentration and increased the bioavailability of hydroquinone relative to normal oil-in-water emulsion creams. Therefore, the high incidence of exogenous ochronosis in South Africa may be directly related to higher concentrations of hydroquinone, combination with other drugs, and increased bioavailability as a result of the predominance of hydroalcoholic lotions.