Lichen planopilaris versus discoid lupus erythematosus: a trichoscopic perspective.

Trichoscopy enables visualization of subsurface structures and color patterns of scalp and hair. Recently, its applications expanded to diagnose inflammatory conditions such as lichen planopilaris (LPP), scalp psoriasis, and discoid lupus erythematosus (DLE). Clinically, both LPP and DLE appear similar as cicatricial alopecia on the scalp making the diagnosis difficult. Here, we report the utility of trichoscopy in the clinical diagnosis of LPP and DLE. Clinically, suspected lesions of DLE and LPP on the scalp of each patient were observed under trichoscopy. Histopathology of lesions confirmed the clinical diagnosis. Authors observed characteristic trichoscopic features in LPP as well as in DLE proving the clinical diagnosis. Hence, trichoscopy can be used to diagnose LPP and DLE clinically avoiding skin biopsy.

INTRODUCTION

The standard methods such as clinical examination, pull test, and skin biopsy vary in sensitivity, reproducibility and invasiveness in the diagnosis of scalp and hair disease. Trichoscopy is a new and valuable tool providing surface and subsurface microscopic views of scalp and hair. This method may fill these lacunae for accurate diagnosis.[1]

Lichen planopilaris (LPP) appears as purplish plaques affecting central scalp. The pull test is positive for anagen at the site of active disease. Atrophy and permanent alopecia of the scalp may result with time.[2]

Discoid lupus erythematosus (DLE) appears as erythematous scaly plaques in the early stages. Then, lesions get thickened with adherent scales and follicular plugging. In late stage, lesions become depressed, depigmented, and telengiectasia.[2]

However, both conditions may be indistinguishable clinically requiring a biopsy to prove the diagnosis. Histopathological changes of early DLE and LPP are different and characteristic. Conversely, in the late stages, features are apparently difficult to differentiate.[345] Hence, trichoscopy plays a significant role in differentiating DLE and LPP on scalp clinically.[6] Here, we are reporting the importance of trichoscopy in the clinical diagnosis of LPP and DLE in two patients.

CASE REPORTS

Case 1

A 27-year-old male presented with hair loss from the scalp since 6 months. Itching and slight burning sensation was present. It was progressive, covering almost entire vertex area extending to the parietal areas. Examination revealed well-defined purplish plaques with atrophy of skin [Figure 1].

Figure 1

Well-defined purplish plaques covering entire vertex of scalp

Trichoscopy showed perifollicular scales (black stars), diminished follicular ostia and white dots (red stars). Blue-grey dots (yellow arrows) around the follicular structures were seen as a “target” pattern [Figure 2].

Figure 2

Trichoscopy showing perifollicular scales (black stars), white dots (red stars) and blue-grey dots (yellow arrows) around the follicular structures were seen as a “target” pattern

Histopathology of a lesion showed infundibular hyperkeratosis, hypergranulosis, bandlike infiltrate of lymphocytes with sparing of interfollicular areas, which are consistent with diagnosis of LPP [Figure 3].

Figure 3

Histopathology showing infundibular hyperkeratosis, hypergranulosis, bandlike infiltrate of lymphocytes with sparing of interfollicular areas (H and E, ×10)

Case 2

A 50-year-old male presented with lesions on the scalp since 4 months. History of exacerbation of lesions on sunlight exposure was present. Examination revealed erythematous scaly plaques on the vertex and frontal areas with atrophy of underlying skin [Figure 4].

Figure 4

Well-defined erythematous scaly plaques on vertex of the scalp

Trichoscopy showed branching capillaries (yellow diamond), white patches (yellow star), keratin plugs (red arrow), reduced follicular ostia and white dots (red stars). Blue-grey dots (yellow arrow) inside the patch of alopecia referred to as “speckles” pattern were also observed [Figure 5]. Histopathology showed thinning of epidermis, hypogranulosis, follicular horny plugs, vacuolar changes and necrotic keratinocytes at the dermoepidermal interface which are consistent with diagnosis of DLE [Figure 6].

Figure 5

Trichoscopy showing branching capillaries (yellow diamond), white patches (yellow star), keratin plugs (red arrow), white dots (red stars) and blue-grey dots (yellow arrow) inside the patch of alopecia referred to as “speckles” pattern

Figure 6

Histopathology showing thinning of epidermis, hypogranulosis, follicular horny plugs, vacuolar changes and necrotic keratinocytes at the dermoepidermal interface. Involvement of interfollicular area is evident (H and E, ×10)

Systemic examination and blood investigations in both patients were unremarkable.

DISCUSSION

Lichen planopilaris is the most common cause of cicatricial alopecia. It frequently affects middle-aged females with irregular areas of atrophic alopecia on the scalp. There will be perifollicular erythema and plugging. The course is often progressive resulting in complete alopecia. The pull test shows painless extraction of anagen roots.[1]

Discoid lupus erythematosus of scalp is uncommon and presents clinically as single or multiple alopecic patches. The affected scalp shows erythema, edema, scaling, follicular hyperkeratosis, atrophy, and telengiectasia.[1]

Histopathological changes of LPP during activity of disease include infundibular hyperkeratosis, hypergranulosis, bandlike infiltrate of lymphocytes and dropping off of necrotic keratinocyte along the follicular basement membrane. Histopathological changes in early DLE lesions are thinning of epidermis, hypogranulosis, follicular horny plugs, vacuolar changes and necrotic keratinocytes at the dermoepidermal interface. Nevertheless, the resolving patches of both conditions exhibit fibrotic tracts at the sites of destroyed follicles.[7] Hence, in the late stages of both conditions, clinical as well as histopathological diagnosis becomes difficult.

In a study of 84 patients with cicatricial alopecia, trichoscopy of suspected DLE lesions showed scattered dark-brown discoloration of the skin, large yellow dots, and thick arborizing vessels.[8] Similar findings were described by the authors, in addition to, honeycomb pigmented network, blue-grey dots ("speckles" pattern) and variable scaling.[69] In other studies, authors state that follicular keratotic plugging is a typical feature of DLE that can be easily appreciated clinically as well as dermoscopically and these may still be present in areas of chronic alopecia.[1011]

Trichoscopy of DLE in our patient revealed similar picture including branching capillaries, white patches, keratin plugs, reduced follicular ostia and white dots. Blue-grey dots were arranged in “speckles” pattern.

Tubular perifollicular scaling, elongated blood vessels, diminished follicular ostia, and white dots were the principal findings in trichoscopy of LPP lesions.[68] Authors observed “target” pattern arrangement of blue-grey dots.[6] Similar trichoscopic features were observed from LPP lesions in our case too.

White dots in both DLE and LPP probably correspond to impending fibrosis around follicle where as white area, characteristic feature of DLE and not LPP is due to tissue fibrosis involving areas between the follicles in the dermis.

Blue-grey dots suggest the melanin incontinence. Target pattern blue-grey dots in LPP indicates circular arrangement of melanin around the perifollicular area sparing the interfollicular area unlike DLE where in, blue-grey dots follow a speckled pattern indicating involvement of interfollicular areas with sprinkling of melanin in these areas.

Honey comb pattern of pigment network which is a feature of LPP was not observed in our case. This is probably because of melanin synthesis inhibition due to inflammatory infiltrate at the site.

In our opinion, follicular plugs, “speckles” pattern of blue-grey dots, white areas are characteristic of DLE and “target” pattern of blue-grey dots, perifollicular scaling are characteristic of LPP. White dots, branching capillaries, reduced follicular ostia are seen in both DLE and LPP.

Thus, trichoscopy plays an important role in distinguishing both DLE and LPP clinically in early as well as in late stages of disease progression. Images documented will help in evaluating the progression of disease and therapeutic response to the treatment.