Nonpruritic, painless, ashen blue-gray macules on the neck and trunk

Erythema dyschromicum perstans (EDP) is an exceptionally rare form of lichen planus. Also referred to as ashy dermatosis, it is a benign, hyperpigmented cutaneous eruption. 
The condition often presents in children and young adults of Asian and Latin American origin...

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Erythema dyschromicum perstans (EDP) is an exceptionally rare form of lichen planus. Also referred to as ashy dermatosis, it is a benign, hyperpigmented cutaneous eruption. 


The condition often presents in children and young adults of Asian and Latin American origin who are predominantly darker-skinned; however, EDP has been found in all age groups and in individuals of all skin coloring.^1-3 Most cases are diagnosed in El Salvador, the site of the first described case.¹

EDP varies in presentation from its earlier stages to its later stages. In the beginning, erythematous and elevated borders emerge around gray macules on the face, neck, trunk, or upper extremities in a symmetrical fashion. These are the active lesions. Patients do not have any related symptoms, either in the areas of the lesions or in the rest of the body. As the lesions progress, they take on a more blue-brown color, and the erythematous border flattens. 


Patients often present with multiple ashy lesions of different shapes and sizes. These lesions persist longer in some patients than in others; in many, the lesions disappear after a few years.^1-3

Although it is not clear why EDP develops in certain individuals, indigenous environmental exposures, such as infection with whipworm or another intestinal parasite, chlorothalonil exposure (in banana farm workers), ingestion of ammonium nitrate found commonly in fertilizers, and contact with other pesticides, are considered to play a role. In instances of whipworm infection, it was found that when individuals were treated for the parasitic infection, EDP subsequently resolved. 


Others have postulated that medications such as benzodiazepines and penicillin may place individuals at greater risk for developing EDP.⁴

Genetic studies have also been conducted, specifically for association with the human leukocyte antigen class II major histocompatibility complex (HLA-DR). In a population of Mexican Mestizo patients, HLA-DR4 was found in 65% of EDP-positive patients, compared with 23% of control subjects.⁵ Although it is not clear that this implies a direct genetic association, it makes for a greater case that there may be a genetic component for the disease.

Because EDP is so uncommon, it can be difficult to diagnose the condition. It is often mistaken for atrophic lichen planus, lichenoid drug reactions, lichen planus pigmentosus, pigmented contact dermatitis, postinflammatory hyperpigmentation, and tuberculoid leprosy. 


Clinical context must be considered in the differentiation of EDP from these other conditions, such as if the patient had begun taking any new medications, if the patient is immunocompromised, the age of the patient, and other comorbidities and exposures of the patient. Additionally, EDP has a characteristic erythematous raised rim around lesions that is nonpruritic and not present on mucosal surfaces. 


For further confirmation, laboratory testing should be conducted to rule out any infectious etiologies, glucose intolerance, and liver dysfunction.

A biopsy of the lesion may also be taken specifically from the raised erythematous border of a macule. However, biopsy results can be nonspecific and limited in value. Histologic examination shows vacuolar degeneration of the basal layer and an upper dermis with increased melanophages. The epidermis shows some thinning and some colloid bodies may be seen.^1-3

Therapeutic intervention is not required for EDP. However, treatment may be considered in a patient with cosmetic concerns. Although many modalities have been tested, none have produced strong results indicative of a clear treatment plan. This is in part limited by sample size, as EDP is so rare and often remits spontaneously in individuals who had it previously. 


Clofazimine, a lipophilic rhimophenazine dye originally developed to treat tuberculosis, holds the most promise. It showed good or excellent response in seven of eight patients maintained on the drug for 3 months, although it is not apparent whether a cure was achieved. This drug targets the initial inflammatory phase of EDP. However, adverse effects can result in difficulties with compliance and undue risk in some patients. Adverse effects of clofazimine include orange discoloration of the skin and eye, development of ichthyosis, potentially fatal enteropathy secondary to crystal deposition in the intestine, eosinophilic enteritis, and splenic infarction.⁶

Antibiotics, ultraviolet exposure, chemical peels, corticosteroids, psychotherapy, and vitamins have shown no improvement in EDP.

In our case, the patient was determined to have EDP because of the classic appearance of her lesions. She opted not to have a confirmatory biopsy. The patient was advised that the lesions can spontaneously disappear and that current treatments often produce disappointing results. The patient opted not to pursue treatment after counseling. 


Shehni Nadeem, BA, is a medical student and Maura Holcomb, MD, is a dermatology resident at Baylor College of Medicine in Houston.


References 


1. Convit J, Kerdel-Vegas F, Rodriguez G. Erythema dyschromicum perstans a hitherto undescribed skin disease. J Invest Dermatol. 1961;36(6):457-462.

2. Cestari TF, Dantas LP, Boza JC. Acquired hyperpigmentations. An Bras Dermatol. 2014;89(1):11-25. Available at ncbi.nlm.nih.gov/pmc/articles/PMC3938350
3. Berger RS, Hayes TJ, Dixon SL. Erythema dyschromicum perstans 
and lichen planus: are they related? J Am Acad Dermatol. 1989;21
(2 Pt 2):438-442.

4. Penagos H, Jimenez V, Fallas V, et al. Chlorothalonil, a possible cause of erythema dyschromicum perstans (ashy dermatitis. Contact Dermatitis. 1996;35(4):214-218.

5. Correa MC, Memije EV, Vargas-Alarcón G, et al. HLA-DR association with the genetic susceptibility to develop ashy dermatosis in Mexican Mestizo patients. J Am Acad Dermatol. 2007;56(4):617-620.

6. Arbiser JL, Moschella SL. Clofazimine: a review of its medical uses and mechanisms of action. J Am Acad Dermatol. 1995;32(2 Pt 1):241-247. 


All electronic documents accessed February 2, 2016.