|Year : 2014 | Volume
| Issue : 2 | Page : 90-94
Lichen planus pigmentosus: A retrospective clinico-epidemiologic study with emphasis on the atypical variants
Rahul Mahajan, Muthu Sendhil Kumaran, Davinder Parsad
Department of Dermatology, Venereology, and Leprology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
|Date of Web Publication||15-Dec-2014|
Muthu Sendhil Kumaran
Department of Dermatology, Venereology, and Leprology, Postgraduate Institute of Medical Education and Research, Chandigarh - 160 012
Source of Support: None, Conflict of Interest: None
Background: Lichen planus pigmentosus (LPP) is a relatively common pigmentary dermatosis which commonly presents as brownish or slate grey patches in diffuse, reticular and blotchy pattern. Recently, linear, flexural, and zosteriform LPP have been described. Methods: The present study was aimed to study the epidemiologic profile of LPP with a special focus on the atypical variants. In this retrospective study, case records of patients diagnosed clinically and/or histopathologically as LPP during the time period from January 2009 to December 2013 were analyzed. Results: Case records of 76 patients were analyzed. The mean age and mean duration of disease were 37.6 years and 3.5 years, respectively, with M:F = 1:2.5. The diffuse pattern of LPP was the most common in 38 (50%) patients followed by reticular in 15 (19.7%), blotchy in 12 (15.7%), and perifollicular in 3 (3.9%) patients. Five (6.6) temporally correlated the onset of LPP with the cosmetic use. The atypical variants included segmental LPP in 3 (3.9%) patients, linear LPP in 3 (3.9%), and flexural in 2 (2.6%) patients. Among three patients with segmental LPP, one had bilateral LPP over breast, one had unilateral segmental LPP, and third had co-localization of segmental LPP and vitiligo. Histopathologic changes included focal basal cell degeneration with sparse upper dermal interface dermatitis along with melanophages in the upper dermis. All patients were treated with mid-potent topical corticosteroids and/or topical calcineurin inhibitors with poor response to therapy. Conclusions: The atypical and localized variants of LPP are not uncommon and like classic LPP respond poorly to treatment.
Keywords: Lichen planus, lichen planus pigmentosus, lichen planus pigmentosus inversus
|How to cite this article:|
Mahajan R, Kumaran MS, Parsad D. Lichen planus pigmentosus: A retrospective clinico-epidemiologic study with emphasis on the atypical variants. Pigment Int 2014;1:90-4
| Introduction|| |
Lichen planus pigmentosus (LPP) is a relatively common pigmentary disease in ethnic skin, the etiology of which is still elusive. Few regard it as a variant of lichen planus (LP) due to its association with classic cutaneous and oral LP and histopatholgic similarities.  Others attribute its occurrence to the use of cosmetics including fragrances, hair dyes, and mustard oil.  Clinically, the disease is characterized by asymptomatic or itchy, slate-grey to black macules (without any erythematous border) present over forehead, pre-auricular region, and flexures. In a large epidemiologic study by Kanwar et al., 124 patients of LPP were described with different morphologic patterns seen which included diffuse in 77% patients followed by reticular (9.7%), blotchy (7.3%), and perifollicular (5.6%).  More recently, several atypical morphologic variants of LPP have been reported including linear LPP,  LPP inversus, , and zosteriform LPP. , The aim of the present study was to further study the epidemiology of LPP in Indian population with a special focus on these unusual variants.
| Methods|| |
This was a retrospective study. Case records of patients who had attended the pigmentary clinic at our institute were screened for recruitment into the study during the time period from January 2009 to December 2013. All patients with a diagnosis of LPP were eligible for recruitment in the study. Diagnosis of LPP was made by a dermatologist mostly on clinical grounds and in doubtful cases, histopathologic examination of skin biopsy specimen was advised.
A detailed history regarding the demographic characteristics (age and sex), duration and evolution of the disease, age and initial site of onset of disease, family history, aggravating or initiating factors (especially the use of mustard/amla oil, hair dyes), associated cutaneous or systemic illness, and the treatment given was recorded. Clinical examination including the extent and pattern of body surface area involvement and the presence of mucosal involvement in all the patients was noted. Histopathological changes were also recorded.
| Results|| |
During the study period, case records of 76 patients with a diagnosis of LPP were analyzed. There were 54 females and 22 males (M:F = 1:2.5). The mean age of the study cohort was 37.6 ± 12.9 years with a mean duration of disease of 3.5 ± 1.8 years. The most common complaint by the patients was the cosmetic disfigurement due to the hyperpigmentation with a minority (10%) reporting significant itching. The face, predominantly the forehead, temples and the pre-auricular region was the most common site to be involved in 31 patients followed by neck in 22 patients, upper limb in 16, trunk in six, and lower limb in two patients. The most common pattern of LPP was diffuse in 38 (50%) patients followed by reticular in 15 (19.7%), blotchy in 12 (15.7%), and perifollicular in 3 (3.9%) patients. In eight patients (10.5%), atypical variants of LPP were seen. These included segmental LPP in 3 (3.9%) patients, linear LPP in three (3.9%), and flexural in two (2.6%) patients. [Table 1] summarizes the demographic, clinical, and histological characteristics of the patients with atypical LPP.
Segmental lichen planus pigmentosus
Among the three patients, two were middle-aged females (32 years and 40 years of age), the third was a 22 years old male. The disease duration ranged from 2 to 5 years. In one patient, the lesions appeared as blotchy macules of bluish grey hyperpigmentation over the right breast [Figure 1]. Over the next 2 years, similar patches appeared over the left breast after which the disease stabilized. These macules were not itchy and were not preceded by any inflammatory papules. Oral and genital mucosa and nails were normal. The second patient had similar greyish blue macules distributed over neck in a segmental pattern. The third patient [Figure 2] was a young adult who developed bluish grey patches in a dermatomal distribution over the right side of the chest; there was no history suggestive of herpes zoster infection over the concerned dermatome. In addition to it, the patient had segmental vitiligo since early childhood in the same distribution.
|Figure 2: Segmental vitiligo with segmental lichen planus pigmentosus|
over the right side of chest and right hand
Click here to view
Linear lichen planus pigmentosus
Three females presented with linear steaks of bluish grey hyperpigmentation over neck and upper chest [Figure 3]. Although all three patients reported frequent use of deodorants and other toiletries, they did not develop any inflammatory lesions prior to onset of pigmentation. Patch test results were negative for Indian standard series. There was no photosensitivity but was associated with minimal itching.
Flexural/Inverse lichen planus pigmentosus
Two females presented with blotchy and at places reticular brownish to grey colored pigmented macules predominantly over flexors. These included the inframammary area, axilla and groins in both the patients [Figure 4]. One patient had lesions of LPP elsewhere too along with oral LP whereas the other patient had sole involvement of flexors. The lesions were minimally itchy and there were no nail changes of LP.
Associated classical cutaneous LP was seen in only five (6.6%) patients and oral LP in another two (2.6%) patients. Associated co-morbidities included hypertension (two patients), diabetes mellitus (three patients), hypothyroidism, and hyperthyroidism (two patients each). Thirty patients (40%) were using toiletries such as henna, p-phenylenediamine containing hair dyes, mustard oil, and amla but only 5 (6.6) temporally correlated the onset of LPP with the cosmetic use. Skin biopsy for histopathologic examination was advised in all eight patients. Findings in all patients included epidermal hyperkeratosis, focal basal cell degeneration with sparse upper dermal interface dermatitis along with melanophages in the upper dermis [Figure 5]. The treatment prescribed included administration of mid-potent topical corticosteroids (fluticasone/mometasone) and/or topical calcineurin inhibitors (tacrolimus 0.1% ointment) for several months. These eight patients were followed up for 6-18 months. In all patients, the disease progression stabilized after initiating treatment but only 3 of 8 patients reported a satisfactory improvement in their skin pigmentation whereas the other five were considered as therapeutic failure and were eventually lost to follow-up.
|Figure 5: Lichen planus pigmentosus: Pre-treatment, hematoxylin and eosin, epidermis shows basal cell vacuolar degeneration, basket weave hyperkeratosis, apoptotic cells, pigment incontinence with lymphocytic infiltrate along basement membrane zone and perivascular, ×20|
Click here to view
| Discussion|| |
Ever since the first description by Bhutani et al.,  the nosologic status and pathogenesis of LPP remains a matter of debate. The classic description is the appearance of slate grey colored macules over face, especially the face and temples, and neck in a middle-aged female. Kanwar et al. reported a slight female preponderance in their study. , However, we observed a greater proportion of patients to be females (M:F = 1:2.5). The reason for a female predominance could be manifold - it could be due to more frequent use of cosmetics among females (which has been incriminated as an etiologic factor) or may be attributed to hormonal factors. The mean age of onset in the present study was similar to those in other studies.  The frequency of cutaneous and/or oral LP was less from that seen in previous studies as was the proportion of patients using cosmetics, henna, hair dyes, mustard oil, and amla oil. Common differential diagnosis for LPP are Riehl's melanosis (RM) or pigmented cosmetic dermatitis which simulates LPP both clinically (especially the perifollicular variant of LPP) and histologically (due to the presence of basal cell degeneration in early stage of RM) and erythema dyschromicum perstans (EDP) which shows an outer palpable erythematous ring surrounding a greyish macule, consipicuously absent in LPP. [Table 2] and [Table 3] summarize the differences between LPP, EDP, and RM.
The morphologic variants observed in the present study included diffuse (50%), reticular (20%), blotchy (15%), perifollicular (5%), segmental (5%), linear (5%), and inverse (5%). As can be noted, the relatively newer or atypical morphologic variants are seen in a significant proportion of patients. We observed that with respect to the demographic features, the characteristics of these atypical and less frequently seen patterns of LPP did not differ from those of the more common ones. Seven of eight patients with atypical variants were females but as seen with the rest of the cohort, they were not significantly associated with either classic LP or cosmetic use. Although Vachiramon et al. described a patient with bilateral LPP associated with hepatitis C infection,  none of our patients had any significant co-morbidities like chronic viral hepatitis or diabetes mellitus. In our study, we too report a case of bilateral segmental LPP localized only to the breast that did not have any significant associated disease. Similarly, none of the patients presenting with LPP in a segmental or dermatomal distribution had a previous history of herpes zoster infection or any inflammatory lesions prior to onset of lichenoid macules. Hong et al. reported two cases of linear LPP and speculated that these may follow lines of Blaschko and hence, related to mosaicism.  One of the patients in the present study who had segmental LPP had associated segmental vitiligo which developed earlier in his childhood. This co-localization of LPP and vitiligo was interesting and could, in fact, be explained by mosaicism. Multiple linear LP lesions following the lines of Blaschko have been reported, and hence, this theory may be investigated for future studies. Moreover, if LPP is considered to be in the spectrum of LP, the linear lesions could be attributed to koebnerization.
Nearly four decades ago, Pinkus coined the term regional lichenoid syndromes that are characterized by lichenoid tissue reaction with epidermal basal cell damage. These include dermatoses showing similar clinical presentation and interface dermatitis on histopathology such as LP, lupus erythematosus, lichenoid drug eruptions, and EDP.  These atypical variants of LPP may well belong to this group. The term LPP inversus (LPPI) was proposed by Pock et al. in 2001, after the report of seven cases of LPP located predominantly on intertriginous areas.  In a minority of patients, additional lesions with features of LP or LPP may be found outside of the flexor surfaces, but they are scarce, accounting for about 10% of all the area affected. In a study by Kanwar et al., flexural involvement including the axilla (8.9%), inframammary folds (6.5%), and groin (3.2%) was seen less frequently.  The lesions in LPPI tend to be more brown than slate-grey as it is postulated that the lichenoid reaction occurs within a short period of time in flexors with dramatically intensive hydropic degeneration of basal keratinocytes.  During this time, the compensatory increased proliferation of keratinocytes cannot develop as in typical LP such that the papules transform quickly into brown macules.
On the basis of available literature, it appears unlikely that LPP occurs as a phenomenon secondary to any infection (isotopic phenomenon) or inflammation (pigmented contact dermatitis). Hence, in our opinion, LPP can be considered as a macular form of LP, which is not related to contact allergy. In comparison to classic LP, the histopathology in LPP shows only focal basal cell degeneration and less intense (and sometimes sparse) upper dermal lymphocytic infiltrate. Although LPP has histopathologic similarities to LP, there are important differences too such as minimal hypergranulosis and relatively sparse upper dermal infiltrate. As has been reported in the literature, the disease tends to be chronic with less than satisfactory response. We treated our patients with topical corticosteroids and/or calcineurin inhibitors for several months without significant improvement. However, the tendency to label any acquired hyperpigmentation of uncertain etiology as atypical LPP should be resisted and when in doubt or atypical cases, the diagnosis should be confirmed on histology.
This write-up portends to exemplify the fact that more localized variants of LPP are not uncommon and hence, better awareness of these entities will lead to more frequent recognition. Whether the disease is a sub-type of LP or a separate entity in itself needs more research and clarification. On the basis of available data, we opine it to be in the spectrum of LP. The disease tends to be frustrating to manage due to the cosmetic disfigurement and relative lack of therapeutic options.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
[Table 1], [Table 2], [Table 3]