|Year : 2016 | Volume
| Issue : 1 | Page : 5-10
Lichen planus pigmentosus: A short review
Irene Mathews1, Devinder Mohan Thappa1, Nidhi Singh1, Debasis Gochhait2
1 Department of Dermatology and STD, Jawaharlal Institute of Postgraduate Medical Education and Research, Puducherry, India
2 Department of Pathology, Jawaharlal Institute of Postgraduate Medical Education and Research, Puducherry, India
|Date of Web Publication||17-Jun-2016|
Dr. Devinder Mohan Thappa
Department of Dermatology and STD, Jawaharlal Institute of Postgraduate Medical Education and Research, Puducherry - 605 006
Source of Support: None, Conflict of Interest: None
Lichen planus pigmentosus (LPP) is a condition characterized by persistent and asymptomatic slaty-gray pigmentation, predominantly in the face. Classically, the pattern is “actinic” with symmetric and diffuse pigmentation in sun-exposed areas, commonly in dark-skinned individuals. It can also rarely present as macular pigmentation of the flexures in the lighter-skinned. LPP is a disease of the middle-aged, with onset in the third to fourth decades of life and few studies show as slightly greater incidence in females. The photo-distributed or actinic pattern, which is more common, is a disease of tropics and Type IV–Type V skin types. Reports are mainly from India, the Middle East, and South America. The inversus type is relatively rare, predominantly occurring in Caucasians. LPP is thought to be a type hypersensitivity IV reaction to unknown antigen with lichenoid inflammation, leading to melanin incontinence and superficial dermal pigmentation. The natural course of the disease is not clear with some cases showing spontaneous resolution, and some cases with persistence of pigmentation for years. In addition, LPP may have marked overlap clinically and histologically with conditions such as pigmented contact dermatitis, differentiation of which may not be possible in routine practice. Because of these issues, as well as the relative rarity of the condition, there is not much evidence on the efficacy of the various treatment options. Currently, none of the available treatment options show consistent responses or a clear superiority to other modalities, the evidence on efficacy being restricted to a few case series.
Keywords: Dermal pigmentation, India, interface dermatitis, lichen planus pigmentosus, melanin incontinence
|How to cite this article:|
Mathews I, Thappa DM, Singh N, Gochhait D. Lichen planus pigmentosus: A short review. Pigment Int 2016;3:5-10
| Introduction|| |
Lichen planus pigmentosus (LPP) is a condition characterized by persistent and asymptomatic slaty-gray pigmentation, predominantly in the face. Classically, the pattern is “actinic” with symmetric and diffuse pigmentation in sun-exposed areas, commonly in dark-skinned individuals. It can also rarely present as macular pigmentation of the flexures in the lighter-skinned. The pigmentation is dermal and occurs without any clinical evidence of inflammation.
Even though there are no preceding papular lesions or significant pruritus, LPP has a well-described association with classical lesions of LP (in about 30%). In addition, histology of LPP is characterized by interface dermatitis with dense lichenoid infiltrate in the dermis with pigmentary incontinence. Hence, it is considered a variant of LP.
However, LPP has significant clinical and histological similarity with conditions such as erythema dyschromicum perstans (EDP)/ashy dermatosis (AD) and pigmented contact dermatitis, making an accurate diagnosis difficult in routine practice.
The pigmentation in LPP in many cases is persistent, and none of the treatment options show definite advantage over the others. The relative rarity of the condition and the fact that the natural course of the disease is not clearly known are issues in conduct of trials to evaluate the treatment options.
| Historical Background|| |
LPP was first reported from India in 1974 by Bhutani et al., describing the clinical and histopathological features in a series of 40 patients. There were also individual cases or small case series of the classical actinic type published from other tropical countries, mainly the Middle East and Latin America. Vega et al. in 1992 presented LPP and AD as two distinct entities with distinguishing clinical and histopathological findings. However, this concept is controversial with many authors either considering these as a single entity.
The second relatively large study of 124 Indian patients was published by Kanwar et al. in 2003, describing the clinical, epidemiological, and histopathological features of LPP in Indian patients. The study revealed no sex predilection, identified head and neck as the common sites of involvement, and described the morphological patterns of LPP in Indian population. It also confirmed the coexistence of classical LP lesions.
The inversus type of LPP was first reported in Europe, followed by reports from Japan. Fewer reports exist from Africa  and India, being common in light-skinned. Overall, inversus type is a rare disease with >30 cases  in published literature. Both classical and inversus patterns of LPP were later considered as a single entity in view of a common clinical picture of mostly asymptomatic pigmentation with lichenoid histology.
| Epidemiology|| |
LPP is a disease of the middle-aged, with onset in the third to fourth decades of life and a few studies show as slightly greater incidence in females. The photo-distributed or actinic pattern, which is more common, is a disease of tropics and Type IV–Type V skin types. Reports are mainly from India, the Middle East, and South America. The inversus type is relatively rare, predominantly occurring in Caucasians.
| Etiopathogenesis|| |
LPP is thought to be a type hypersensitivity IV reaction to unknown antigen with lichenoid inflammation, leading to melanin incontinence and superficial dermal pigmentation.
Pock et al. hypothesized that an intensive lichenoid reaction occurs quickly before the compensatory increased proliferation of keratinocytes develops as in typical LP, due to which there is a rapid transformation of papules into brown macules. The contributory factors in its causation probably include sun exposure and photosensitizing topical agents in the actinic variant. Topical application of mustard oil, which contains allyl isothiocyanate, a potential photosensitizer, and amla oil, has been proposed as possible inciting agents., Koebnerization due to friction in the flexures or due to tight clothing is thought to contribute to the inversus type of LPP. Majima et al. reported the disappearance of lesions after the discontinuation of wearing tight underclothes among two Japanese patients.
There are a few reports of association of hepatitis C virus infection with LPP., In a series of 33 patients in a Tertiary Care Center in Kuwait, 20 out of 33 patients had a positive hepatitis C virus serology.
| Clinical Features|| |
LPP manifests as pigmentation of insidious onset without any features of inflammation or preceding raised lesions. It is typically asymptomatic although occasionally can have mild pruritus. The course is variable with some cases showing spontaneous resolution within weeks to months. It may be persistent over years in many. Surprisingly, there is no involvement of scalp, mucosa, or nails.
The classical type of LPP is characterized by slaty-gray to brownish-black pigmentation symmetrically over photo-exposed areas, most commonly face and neck, followed by upper limbs. More extensive lesions and truncal involvement are rare [Figure 1]. Although the pigmentation usually is diffuse,, reticular, blotchy, perifollicular, annular, and gyrate patterns are also encountered., There are isolated case reports of linear unilateral hyperpigmentation in the extremities (Blaschkoid), and segmental patterns on the trunk. A study in Indian patients by Kanwar et al. revealed that while a majority of 77.4% showed diffuse pigmentation, a few also showed reticular (9.7%), blotchy (7.3%), and perifollicular (5.6%) patterns. Most commonly, the lesions were bluish-black color in 46% typical of dermal pigmentation patients, slate-gray in 29%, dark brown in 15.3%, and brownish-black in 9.7%. There was no color variegation, with each patient having a single color at all affected sites, the darker colors correlating with a longer duration of the pigmentation and increased sun exposure.
|Figure 1: Slaty-gray pigmented patches with a few lichenoid papules over the neck and chest|
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The flexural variant has round to oval hyperpigmented macules in axilla [Figure 2], groin, submammary areas, and abdomen. Annular lesions have been present in a number of published cases and are commonly observed in both the inversus and actinic forms of the disease.
Thirty percent of LPP cases can have associated classical LP lesions.
| Dermoscopy in Lichen Planus Pigmentosus|| |
Dermoscopy of LPP lesions has revealed pigmentation in different nonspecific patterns.
Friedman et al. described pigmentation in lesions of LPP inversus as diffuse, dotted, and mixed patterns. Diffuse pattern referred to structureless areas of brown pigmentation, probably epidermal pigmentation. Dotted pattern described fine or coarse blue-gray dots of indicating dermal melanophages, and mixed pattern referred to lesions showing both epidermal and dermal components. The presence dotted pattern correlated with a tendency for the pigmentation to persist.,
| Histopathology|| |
The histopathology of LPP forms a continuous spectrum with the earliest lesions showing marked inflammation at the interface, which later subsides, leaving behind the characteristic dermal pigmentation in older lesions., The epidermis is usually atrophic as opposed to acanthosis occurring in LP.
The inflammatory phase is characterized by a dense band of lymphohistiocytic inflammatory infiltrate in the upper dermis with prominent basal-vacuolar degeneration [Figure 3]. Some melanin incontinence is seen with scattered dermal melanophages. The second pattern of burnt-out inflammation shows only a minimal superficial perivascular lymphohistiocytic infiltrate and focal to absent basal-vacuolar degeneration. However, there is marked melanin incontinence with many interstitial and perivascular melanophages. Colloid bodies are a common finding in LPP as in LP. CD8+ lymphocytes may be a prominent component in the infiltrate
|Figure 3: Histopathology photomicrograph showing interface dermatitis with melanin incontinence (H and E section, ×400)|
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Immune deposits are not as consistently or commonly found in LPP as in classical LP. Around 15% of cases show immune deposits. The patterns seen include immunoglobulin M (IgM) (less commonly immunoglobulin G [IgG]), C3, and fibrinogen deposits in the colloid bodies, as well as linear IgM and C3 deposits along the basement membrane zone.,
| Differential Diagnoses for Classical Lichen Planus Pigmentosus|| |
Erythema dyschromicum perstans/ashy dermatoses
Classical LPP and EDP have a similar predilection for middle-aged dark-skinned individuals. Clinically, it can be distinguished from LPP by a more widespread distribution beyond the sun-exposed areas. Extensive involvement over covered areas such as the trunk is common. Generalized hyperpigmentation could develop in the late stage of EDP.
An early inflammatory phase is typically described with erythema of the lesions. However, the classical description of thin evanescent erythematous halo around the macular pigmentation is rarely observed. The pigmentation itself can evolve into circinate and annular patterns with central clearing which are typical of EDP.
Histopathologically, EDP shows basal vacuolar degeneration with dermal mononuclear infiltrate. However, the infiltrate is not lichenoid but periadnexal. A few authors also opine that the pigmentation is in deeper dermis compared to the dermal pigmentation in LPP.
Colloid bodies are typical of LPP but occasional in EDP. Direct immunofluorescence (DIF) in active lesions of AD has been reported as positive for IgM, IgG, and fibrinogen, and C3 staining of colloid body is also seen in LPP.
However, many authors do not consider EDP as a distinct entity. Differentiating features are given in [Table 1].
|Table 1: Differentiating features between lichen planus pigmentosus and erythema dyschromicum perstans|
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Pigmented contact dermatitis/Riehl's melanosis
Pigmented contact dermatitis (PCD) is noneczematous variant of contact dermatitis due to repeated contact to small amounts of allergen in textiles, fragrances or washing materials. Diffuse or patchy brown pigmentation with predilection for the face and forehead occurs.
Presentation is similar to LPP with patchy ill-defined pigmentation. Histology is indistinguishable from LPP with interface dermatitis, lichenoid infiltrate, and melanin incontinence. Even DIF findings may be found similar to LPP. The diagnosis may be suggested clinically by prior history of topical application (medications, cosmetics, and dyes). A definitive diagnosis of PCD can only be established with a positive patch identifying the allergen.
Hence, all diagnoses of LPP/EDP can be considered definitive only after ruling out PCD. This requires patch testing for all possible allergens based on a detailed exposure history.
It is particularly important in management of apparently persistent and treatment-refractory cases of LPP/EDP as these might actually be PCD with continued allergen exposure.
Clinical characteristics, histopathology, and DIF results which have been claimed in literature as specific findings in AD and LPP do not rule out truly cases with pigmented contact allergy.
Melasma is characterized by symmetrical pigmentation in sun-exposed areas; most commonly, face, with rare involvement of the “v” of neck and forearms. The pigmentation can be epidermal, dermal, or mixed and based on areas affected, it may be centrofacial, mandibular, or maxillary.
Pregnancy (chloasma) and hormonal therapy are common etiological factors in this condition, as such melasma has a strong female predilection.
This pigmentation which can persist up to 6 months after the infection consists of freckle-like macules or a diffuse slaty-gray pigmentation in the malar area and root of the nose. Biopsy shows diffuse hypermelanosis of the entire epidermis without any interface inflammation or dermal pigmentation.
It is characterized by hyperpigmented velvety plaques of the flexures; commonly the neck, axilla, and occasionally the groin. Commonly an indicator of underlying insulin resistance, it can also be a paraneoplastic manifestation. Other sites uncommonly involved are the face or dorsum of the hands, especially in the hereditary forms.
Grayish pigmentation of the skin may occur due to deposition of drugs which include topical hydroquinone (exogenous ochronosis), argyria, hydroxychloroquine, chloroquine, amiodarone, and minocycline.
Exogenous ochronosis occurs as a diffuse pigmentation which can be seen as minute blue macules in a reticulate pattern under magnification. It is commonly seen on the face which follows long-term use of skin-lightening creams containing hydroquinone, with accentuation of the photo-exposed areas, sparing the creases of the face. Biopsy shows banana-shaped yellow-brown granules in and around collagen bundles along with foreign body type granulomatous reaction.
There is history suggestive of preexisting inflammation. In addition, the pattern of pigmentation may provide clues to underlying condition. The lesions are ill-defined and may show areas with patchy hypopigmentation.
Cutaneous amyloid deposition occurs as a result of chronic friction such as scratching or using abrasive materials for scrubbing the skin. It presents as an asymptomatic brown pigmentation with a rippled appearance and the shoulder is a common site. Diagnosis is usually clinical and can be confirmed by histology which shows amyloid deposition in the dermal papillae.
Nevus of Ota and Hori acquired bilateral nevus of Ota-like macules
Nevus of Ota manifests around puberty when the dermal melanocytes pigment under the influence of the hormonal spurt. These dermal melanocytes represent a defect in migration of melanocytes from the neural crest to the epidermis. It is almost always unilateral with blue-gray pigmentation in the ophthalmic and maxillary distribution of the trigeminal nerve, including the skin, eye, and oral mucosa.
Hori nevus or acquired bilateral nevus of Ota-like macules manifests in adults with a speckled or confluent brownish-blue or blue-gray pigmentation of temples, malar area (where it mimics melasma), root of the forehead, eyelids, and alae-nasi. Biopsy shows spindle-shaped dendritic melanocytes in the dermis.
| Differential Diagnosis of Lichen Planus Pigmentosus Inversus|| |
Fixed drug eruption, postinflammatory pigmentation, acanthosis nigricans, and AD should be considered differentials in a case of flexural pigmentation.
| Associations|| |
There are isolated reports of LPP in association with hepatitis C,, nephrotic syndrome, and acrodermatitis of Bazex.
| Treatment|| |
The natural course of the disease is not clear with some cases showing spontaneous resolution and some cases with persistence of pigmentation for years. In addition, LPP may have marked overlap clinically and histologically with conditions such as PCD, differentiation of which may not be possible in routine practice. Because of these issues, as well as the relative rarity of the condition, there is not much evidence on the efficacy of the various treatment options.
Currently, none of the available treatment options show consistent responses or a clear superiority to other modalities, the evidence on efficacy being restricted to a few case series.
Management includes avoidance of exacerbating factors which includes photoprotection in the actinic variant. In the inversus variant, measures to reduce friction in the body folds such as weight reduction and avoidance of tight clothes are advisable.
Topical steroids have been commonly used but are of doubtful efficacy.
Topical tacrolimus, specific suppressor of T-cell mediated inflammation, is considered a reasonable treatment option.
A nonrandomized open label study on efficacy of topical tacrolimus (0.03%) used for 4 months showed improvement in seven out of thirteen patients, with effects starting at 8 weeks. Earlier reports of poor response to tacrolimus had tried application for shorter durations. Hence, further studies are warranted.
Since the clearance of the lesion is seldom complete, the use of lasers or their combination with topical agents can be considered.
A report on use of low-fluence Q-switched Nd-YAG (1064 nm) in 3 weekly sessions, combined with 0.1% tacrolimus, in linear LPP of the forehead, for a total duration of 4 months showed complete clearance of pigmentation, with no recurrence at 6 months of follow-up.
Systemic treatment modalities have also been tried including systemic corticosteroids and Vitamin A. The use of dapsone may halt the progression of pigmentation according to some authors. Combining it with topical tacrolimus may be a reasonable option, especially in cases with extensive pigmentation.
| Prognosis|| |
Course is highly variable. Pigmentation may last only a few weeks and then resolve spontaneously. Sometimes, it may last months to years and be refractory to treatment. This unpredictable course, added to the rarity of the disease and marked overlap with conditions such as EDP, has prevented proper comparative studies between different treatment options.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]