Pigment International

REVIEW
Year
: 2019  |  Volume : 6  |  Issue : 1  |  Page : 4--8

Current understanding of lichen planus pigmentosus, erythema dyschromicum perstans (ashy dermatosis), and idiopathic eruptive macular pigmentation


Michelle Rodrigues1, Amit G Pandya2, Marcel Bekkenk3, Davinder Parsad4, Sujith P Kumarasinghe5,  
1 St. Vincent’s Hospital; The Skin and Cancer Foundation; The Royal Children’s Hospital, Melbourne, Victoria, Australia
2 Department of Dermatology, Fiona Stanley Hospital and University of Western Australia, Perth, Western, Australia
3 Department of Dermatology, Netherlands Institute for Pigment Disorders, Academic Medical Centre, Amsterdam, The Netherlands
4 Department of Dermatology, Venereology and Leprology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
5 Department of Dermatology, University of Texas Southwestern Medical Center, Dallas, Texas, USA

Correspondence Address:
Dr. Michelle Rodrigues
Department of Dermatology, 41 Victoria Parade, Fitzroy 3065, VIC
Australia

Abstract

Lichen planus pigmentosus, erythema dyschromicum perstans and idiopathic eruptive macular pigmentation are the three most commonly accepted subtypes of acquired dermal hyperpigmentary disorders. While some patients fit easily into one of these subtypes, others do not. Overlapping features of several subtypes may also be seen in the one patient. This paper covers these three entities in detail and highlights the diagnostic and classification challenges.



How to cite this article:
Rodrigues M, Pandya AG, Bekkenk M, Parsad D, Kumarasinghe SP. Current understanding of lichen planus pigmentosus, erythema dyschromicum perstans (ashy dermatosis), and idiopathic eruptive macular pigmentation.Pigment Int 2019;6:4-8


How to cite this URL:
Rodrigues M, Pandya AG, Bekkenk M, Parsad D, Kumarasinghe SP. Current understanding of lichen planus pigmentosus, erythema dyschromicum perstans (ashy dermatosis), and idiopathic eruptive macular pigmentation. Pigment Int [serial online] 2019 [cited 2019 Sep 21 ];6:4-8
Available from: http://www.pigmentinternational.com/text.asp?2019/6/1/4/262043


Full Text



 INTRODUCTION



This article describes the three most commonly accepted subtypes of acquired dermal hyperpigmentary disorders. Although some patients easily fit into one of these subtypes, others do not. The overlapping features of several subtypes may also be seen in one patient. Postinflammatory hyperpigmentation, especially in those with skin of color, presents another challenge for the treating clinician who must exclude this diagnosis. Histology of late-stage lesions of these conditions shows similar patterns, making distinction even harder.

Lichen planus pigmentosus (LPP), erythema dyschromicum perstans (EDP), and idiopathic eruptive macular pigmentation (IEMP) often cause confusion, even among experts dealing with pigmentary disorders. The term “ashy dermatosis” (AD) is also used to describe what is agreed by most authorities to be the same condition as EDP. Therefore, in this article, EDP will be used synonymously with AD. To date, the medical literature has not clarified the differences between these entities, with the descriptions of LPP being referred to as EDP or vice versa. In addition, cases reported as IEMP have not always fulfilled the diagnostic criteria for this condition. Experts in pigmentary disorder have formed an international consensus group. The group is still vigorously debating what, if any, clinical and histological differences exist between these conditions and are formulating methods by which disease patterns can be recorded and clinical differences can be refined. This review aims to summarize our understanding of the presentation of these three conditions and how they clinically and histologically differ to help identify problems in the nomenclature, diagnosis, and treatment of this confusing group of pigmentary conditions.

Lichen planus pigmentosus

There are only a few features that have been described to distinguish among LPP, EDP, and IEMP [[Table 1]]. LPP tends to be seen in the middle-aged people of South Asian and Middle Eastern origin.[1] EDP, on the contrary, mostly occurs in those with skin phototypes II to IV (e.g., Latinos and Asians) in the 2nd to 3rd decades of life. This observation is based on the number of reports from various regions of the world, which unfortunately have ascertainment or sampling, bias, which can be corrected with larger, global epidemiological studies. LPP presents in both photoexposed and photoprotected areas with brown–gray macules without erythematous borders. The lesions are usually on the head, neck, axillae, and upper and inner thighs. EDP, in contrast, usually presents predominantly on the trunk as asymptomatic blue–gray discrete macules, sometimes with erythematous borders, especially in early lesions [[Figure 1] and [Figure 2]].{Table 1}{Figure 1}{Figure 2}

Histopathological evaluation reveals superficial dermal melanin and melanophages in LPP, whereas EDP usually has deep dermal melanophages, giving rise to the characteristic brown–gray color in LPP and the bluish-gray hue in EDP.[1] LPP also reveals epidermal atrophy, and in early lesions, basal layer vacuolation with a perivascular lymphocytic infiltrate is seen on biopsy.

However, histopathology alone does not distinguish the three conditions as the older lesions of all three clinical patterns of acquired macular pigmentation can have similar pathology of dermal melanophages with sparse dermal lymphocytic infiltrate without active basal cell vacuolar changes or active interface dermatitis.

LPP is thought by many authors to be a rare variant of lichen planus. Although the exact etiopathology of LPP remains elusive, the presence of lesions on the head and neck region has led some to believe ultraviolet light may be implicated.[2] However, as lesions occur in sun-protected areas such as the submental region, eyelids, retro-auricular skin, and axillae, this argument is unsustainable. In addition, mustard and amla oil have been reported as possible causes.[3] Such oils are frequently found in over-the-counter products such as massage oils, cooking oils, and hair care preparations in India. Allyl thiocyanate is a known photosensitizer in mustard oil and may be a pathogenic agent in LPP. However, most patients with LPP, even in South Asia, do not have any history of exposure to the above agents.

LPP is frustrating for the patient and clinician alike, with pigmentation persisting for years and even decades in many patients despite the use of various medical and physical therapies. The importance of photoprotection cannot be underestimated in attempting to blur the difference between affected and unaffected skin. Patients should be encouraged to seek shade and utilize a broad-brimmed hat, especially when solar radiation is at its peak. The application and reapplication of broad-spectrum sunscreen every 2 h with a sun-protection factor of at least 30+ should be routine. Given visible light has demonstrated a greater ability to cause a sustained darkening in those with skin phototypes IV to VI, sunscreen with a visible light blocker such as iron oxide should also be encouraged in this group.[4]

Various small studies reveal that topical tacrolimus (0.03% twice per day), topical and systemic corticosteroids, and topical vitamin A may be helpful in LPP.[5] Combinations of the above-mentioned therapies have also been used to prevent the progression of LPP. Anecdotal reports of oral isotretinoin and phototherapy have been described for treatment of this condition, and recently, Muthu et al.[6] reported above 50% improvement in 21.8% of patients treated with 20-mg isotretinoin daily for 6 months. Further studies, however, are needed to find better treatments for LPP.[8]

Erythema dyschromicum perstans/ashy dermatosis

EDP (also known as AD) was first described in the 1950s by Ramirez in El Salvador.[7] It is most commonly seen in women in Latin America and Asia.[8] Although most studies cite onset in the 2nd to 3rd decades of life, a recent Korean case review revealed a slightly later onset (3rd to 4th decades).[1]

EDP usually presents with nonpruritic widespread well-demarcated bluish-gray macules. In the initial inflammatory phase, an erythematous border that slowly expands may be noted. The involvement of the face, neck, limbs, and trunk has been described. EDP involves the trunk most commonly unlike LPP in which the involvement of the trunk is less common [[Figure 2] and [Figure 3]]. Although “unilateral” EDP has been reported,[9] it is unlikely that this diagnosis is correct, as many skin lesions can cause acquired hyperpigmentation on one side of the body, including lichen planus and postinflammatory hyperpigmentation.{Figure 3}

The timing of the skin biopsy is important, as the histological features of EDP vary depending on the age of the lesion. Initially, papillary dermal edema and basal layer vacuolation with a perivascular infiltrate can be seen. Later, the density of the inflammatory cell infiltrate decreases with a concomitant increase in melanin incontinence and melanophages in the dermis.[2]

Many drugs can induce patchy macular skin pigmentation that is almost clinically indistinguishable from EDP/AD picture. It is known that even commonly used drugs, such as omeprazole, can cause AD-like acquired macular pigmentation.[10],[11] As such, a careful drug history is essential. If a drug is suspected, it should be avoided.

Unfortunately, as the name suggests, EDP is chronic, progressive, and a challenge to treat. Unsurprisingly, although hydroquinone and tretinoin are helpful in pigmentary conditions such as melasma and postinflammatory hyperpigmentation, they have not demonstrated significant lightening in EDP, where the pigment resides in the dermis.[12] Dapsone (100 mg daily), for 8 to 12 weeks, has been reported to lighten pigmentation and even cause complete resolution.[13],[14] Clofazamine (100 mg daily) demonstrated efficacy in a small study, but the anecdotal experience among experts of pigmentary disorders globally has not been so positive.[15] Although many other treatments have been evaluated, including topical steroids and chloroquine, none of them have resulted in appreciable lightening. Laser treatment has recently been studied by a group in the Netherlands who concluded that fractionated laser was unsuccessful for the treatment of EDP.[16]

Idiopathic eruptive macular pigmentation

IEMP is a rare pigmentary disorder of children and adolescents initially described by Degos et al.[17] The first report of IEMP in English was in 1996 by Sanz de Galdeano et al.[18] who reported a series of five cases.

Multiple well-defined asymptomatic brown–gray macules and slightly raised plaques are most commonly seen on the face, trunk, and proximal extremities in those affected by IEMP [[Figure 4] and [Figure 5].[19] No preceding inflammation, erythema, scale, or itch is noted by the patient. After a variable period of time, the lesions spontaneously resolve without permanent sequelae.[19] Again, increased melanin and melanophages are seen in the dermis. In some patients with IEMP, there are raised velvety thickened plaques. This subset, described by Joshi et al., is known as IEMP with papillomatosis, because epidermal papillomatosis is a characteristic histologic finding.{Figure 4}{Figure 5}

Sanz de Galeano et al. proposed the following diagnostic criteria for IEMP:Eruption of brownish-black discrete, nonconfluent asymptomatic macules on neck, trunk, and proximal extremities in children and adolescentsBasal-cell hyperpigmentation of the epidermis with dermal melanophages without any basal-cell damage or lichenoid infiltrateAbsence of preceding inflammatory lesionsNo previous drug exposureNormal mast cell count

In 2015, Joshi et al.[20] proposed slight modifications to criterion points 1 and 2:Eruption of brownish-black discrete, nonconfluent asymptomatic macules and/or slightly raised plaques that resemble acanthosis nigricans and involve the face, neck, trunk, and proximal extremities, with complete resolution after months or yearsAffects mostly children and adolescents, that is, the first 2 decades of lifeEpidermal hypermelanosis with or without papillomatosis as the main histological finding with the absence of dermal inflammation

According to Joshi et al.,[19] numerous dermal melanophages and the presence of interface changes should not be observed on biopsy, and if observed, are considered to be against the diagnosis of IEMP.

In a commentary published in the same issue of the journal, Kumarasinghe[21] pointed out that although there is no doubt that some cases of acquired small macules of hyperpigmentation have some raised lesions with histopathological features of papillomatosis, the vast number of cases do not have raised lesions at all. Therefore, it may not be prudent to change the diagnostic criteria established by Sanz de Galdeano. Furthermore, many cases of IEMP have melanophages in the dermis. Therefore, the absence of dermal melanophages cannot be an exclusion criterion for IEMP. This confusing nomenclature coupled with contradictory clinical and histological criterion between authors highlights the need for consensus on what constitutes the diagnosis of IEMP. In general, IEMP tends to affect children and adolescents more than LPP and EDP, manifests as smaller lesions than EDP, predominantly occurs on the trunk and proximal extremities, unlike LPP, and spontaneously resolves in most cases, unlike both EDP and LPP.

Examination of the literature reveals the confusion between these conditions and highlights the need for consensus on the clinical, morphological, and histological features to define these entities. Once this is performed, the evaluation of treatment modalities can also be studied.Lichen planus, fixed-drug eruption, and postinflammatory hyperpigmentation, among others, have been confused as IEMP in the literature. LPP and EDP are terms that have been used to describe variable morphological entities over time, but there are many overlapping features. This has created blurred lines between these entities. A global forum on AD, EDP, and LPP has been established to arrive at a consensus on the terminology of these types of acquired macular pigmentations of uncertain etiology and encourage further research.[14],[21] There is a clear need for a large-scale, multicenter worldwide study to further delineate these two conditions etiologically, morphologically, and histologically. The second step will be large, double-blinded randomized studies to accurately assess the efficacy of various treatments for these acquired dermal melanoses.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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