Erythema dyschromicum perstans
What is erythema dyschromicum perstans?
Erythema dyschromicum perstans is also called ashy dermatosis (of Ramirez), because of its colour. It is a benign skin condition characterised by well-circumscribed round to oval or irregular patches on the face, neck and trunk that are grey in colour. They may be symmetrical in distribution or unilateral.
Early lesions may be reddish in colour, often with a more pronounced border, and they may be somewhat elevated. However, this phase is not always observed.
The patient is otherwise well with no associated disease or blood test abnormality.
Who gets erythema dyschromicum perstans?
Erythema dyschromicum perstans most often affects darker skinned patients, most frequently Latin Americans and Indians. However it has also been reported in people of lighter skin colour and various ethnicities.
Erythema dyschromicum perstans may occur at any age but it appears to be more frequent in young adults. Women are affected more often than men.
What causes erythema dyschromicum perstans?
The exact cause for the disease remains unidentified. It is often classified as a variant of lichen planus because of its histopathological features. Over the years, theories have included:
- Genetic susceptibility
- Toxic effects of chemicals such as ammonium nitrate or barium sulphate
- Whipworm infestation
- Viral infections
- Adverse effect of drugs and medications
What is the differential diagnosis?
Several other skin conditions may appear similar to erythema dyschromicum perstans because they also result in discoloured skin patches.
- Lichen planus pigmentosus (erythema dyschromicum perstans may be a variant of this disorder)
- Multiple lesions of fixed drug eruption
- Postinflammatory hyperpigmentation
- Urticaria pigmentosa
- Incontinentia pigmenti
How is it diagnosed?
In some cases the clinical picture may be classical enough to diagnose the condition. A skin biopsy may need to be performed in other cases to aid diagnosis. This may reveal minor vacuolar degeneration of the basal layer in early lesions, and pigmentary incontinence with dermal melanophages in more established patches.
What is the treatment?
Unfortunately erythema dyschromicum perstans is rather resistant to currently available treatments. It may persist unchanged for years although some cases eventually clear up by themselves.
Treatments that may help improve the appearance include:
- Topical steroids
- Exposure to ultraviolet radiation
- Pigment lasers e.g., Q-switched ruby laser
- Chemical peels