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 grey, round to oval or irregular patches distributed on the trunk, extremities and face.

Early lesions maybe 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.

Erythema dyschromicum perstans

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
• Pinta
• Leprosy

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 and pigmentary incontinence.

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

The most successful systemic treatment has been clofazimine. dapsone, griseofulvin, hydroxychloroquine, isoniazid and corticosteroids have been used successfully in a few cases.