Exogenous Ochronosis
There are two types of ochronosis: endogenous and exogenous. The endogenous variety is an autosomal recessive disease, that is caused by a the lack of homogenistic oxidase enyme. Exogenous ochronosis is an avoidable dermatitis, that can be caused by the topical application of compounds such as hydroquinone or phenols. It was first seen in 1912, when a patient who used phenol on a leg ulcer was found to have this condition by Beddard and Plumtre. Hydroquinone induced exogenous ochronosis was found by Findlay in 1975, who observed the condition in patients who used skin lightening creams containing the compound.
There are three clinical stages of exogenous ochronosis:
- erythema and mild hyperpigmentation
- hypergimentation and ‘’caviar-like’’ lesions
- papulo-nodular lesions
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