Erythema dyschromicum perstans (Ashy dermatosis)

 Dear colleagues, I would like to present this case of Erythema dyschromicum perstans to contiue our valuable discussion for the case “A lady with a violaceous lesions”.

This patient is a 35 year old Saudi lady that has a gray-blue ill defined discoloration on neck, face and proximal arms for 7 years. These lesions are preceded by itch erythema.The patient received many ways of treatments including topical hydroquinones, Kligman formula and others.She came to the dermatology clinic for Laser or chemical peel treatment.

4 mm punch Skin biopsy from Rt submental area(hidden area) was done (Blue Nylon sutures can be seen  in the photo) was done.Histology showed normal basket weaven stratum corneum, focal interface with exocytosis of lymphocytes within the epidermis, no band like lymphocytic infiltrate but dense perivascular melanophges (the deep deposition of melanin gives this blue-gray hue according to Tendal’s phenomenon).No eosinophils were seen(drug eruption was ruled out and the patient is on no medication from the clinical history) .These pathological findings are typical for erythema dyschromicum perstans.This disease is differentiated from Lichen planus by the normal basket weaven stratum corneum, the abscence if lichenoid lymphocytic infiltrate and colloidal bodies and the abscence of focal hypergranulosis and saw teeth rete ridges.

 

I started her on topical and systemic steroids for 1 month, the itching and erythema(new lesions developing at forearms-not shown-) cleared completely but the dyspigmentation persisted, topical steroids were continued for another 2 months but the patient did not show up again.

I choosed to give her topical steroids to seal the basement membrane which is the source of the pigment incontinence , obviously peeling will not work, hydroquinon could be given to slow down the formation of new melanin, Q-SWITHCHED laser role in this case is not effective because this is an inflammatory disease and the pigment will come back or even get worse.

what I would like to emphasize in this case that skin biopsy should be done for any suspicious case of erythema dyschromicum and no laser trial to be done for non responding inflammatory dermatosis.