Trichoscopy and histopathology of follicular keratotic plugs in scalp discoid lupus erythematosus.

Dermoscopy has become an integral part of diagnosing scalp disorders including discoid lupus erythematosus (DLE). Follicular keratotic plugs are a marker of DLE and correlate with the hyperkeratosis and plugging of the follicular ostia with keratotic material. They may be present in acute or chronic lesions and their presence alone or in conjunction with other described dermoscopic features can lead to timely diagnosis and initiation of treatment. We present three cases of scalp DLE and discuss the clinical, dermoscopic and histopathologic features.

INTRODUCTION

Dermoscopy has become an integral part of diagnosing scalp disorders and differentiating cicatricial from noncicatricial alopecia. Discoid lupus erythematosus (DLE) is seen in 50 to 85% of patients with cutaneous lupus erythematosus, and scalp involvement is most often the presenting symptom.[1] Accurate and rapid diagnosis is critical and if left untreated, scarring and atrophy commonly occur. Dermoscopic findings described in scalp DLE include follicular red dots, reduced follicular ostia, arborizing vessels, white patches, honeycomb pigmented network, blue-grey dots, and variable scaling.[2-4] Follicular keratotic plugging is a typical feature of DLE that can be easily appreciated on clinically and dermoscopically.[3] Clinically, the keratotic plugs have been referred to as the carpet tack sign since they project up similar to carpet tacks. We present here a case series of three females affected by scalp DLE with prominent follicular plugging on dermoscopy and corresponding keratotic plugs on pathology. All dermoscopic images were obtained with the handyscope (handyscope for iPhone 4, FotoFinder, Bad Birnbach, Bavaria, Germany).

CASE REPORTS

Case 1

A 40-year-old African American female with long-standing scarring alopecia presented to our clinic [Figure 1]. Clinical examination revealed scarring alopecia of the vertex of the scalp with complete loss of pigmentation in the involved scalp except for sparing of a few pigmented patches. Some areas of alopecia had an atrophic appearance but other areas showed prominent follicular plugging. Dermoscopy showed reduced follicular density and numerous yellow keratotic follicular plugs [Figure 2]. A dermoscopy-guided 4 mm punch biopsy from the scalp area exhibiting the prominent follicular plugging was obtained. Horizontal sections were bisected at the level of the lower follicle and multiple sections were examined on hematoxylin and eosin (H and E). At the level of the fat and dermis, there were no follicles visualized. In the dermis, there were dense nodular collections of lymphoid cells surrounding vessels and adnexal structures. At the level of the infundibulum, many infundibular ostia were filled with keratotic material (follicular plugs) [Figure 3]. There was an interface lymphocytic infiltrate of the infundibular ostia and around the sweat ducts. In vertical sections, the epidermis showed orthokeratosis with hyperkeratosis and vacuolar changes of the basal layer. There were dense nodular aggregates of lymphoid cells around the sweat glands. In the fat, hyalinization with some follicular scars containing lymphocytes was present.

Figure 1

Case 1 – Scarring alopecia of the scalp associated with diffuse hypopigmentation, sparse follicular plugs, and diffuse scaling at the borders of the alopecic areas

Figure 2

Case 1 – Dermoscopy guided biopsy, the area shows numerous yellow keratotic plugs

Figure 3

Case 1 – Horizontal section at the level of the infundibulum demonstrates infundibular ostia filled with keratotic material (follicular plugs) (H and E, ×4)

Case 2

A 58-year-old female presented with a five-month history of worsening alopecia on her scalp. Physical examination revealed hypopigmented, atrophic plaques on her upper arms, and well-defined, scaly, patches of alopecia on her scalp. Dermoscopic evaluation of the scalp lesions showed prominent follicular keratotic plugging. Punch biopsies of both skin and scalp lesions were consistent with DLE. Vertical sections of her scalp demonstrated loss of hair follicles replaced by follicular scars and few follicles with dilated infundibulums filled with keratin (keratotic plugs). There was an interface infiltrate of lymphocytes and some plasma cells in a perifollicular and perivascular distribution, with some of the aggregations forming germinal-like centers. At the dermoepidermal junction, there was significant interface dermatitis with pigment incontinence.

Case 3

A 39-year-old female presented with rapidly progressing alopecic patch of the scalp for the past four months [Figure 4]. Dermoscopic examination of her scalp showed polymorphous vasculature, white patches, follicular keratotic plugs, and follicular hyperkeratosis [Figure 5]. A dermoscopy-guided 4 mm punch demonstrated hyperkeratosis with follicular plugging. The follicles had a patulous orifice and there was marked vaculolar alteration of the basal layer and a superficial and deep lymphocytic and histiocytic infiltrate, deeper around adnexal structures.

Figure 4

Case 3 – Alopecic patch showing erythema and pigmentation

Figure 5

Case 3 – Dermoscopic images showing follicular keratin plugs

Follicular keratotic plugs are a marker of DLE and were originally described as a sign of early and active lesions and not in areas of scarring or healed skin.[3] They correlate with the hyperkeratosis and the plugging of follicular ostia with keratotic material. We would like to note that follicular keratotic plugs may still be present in areas of chronic alopecia. Their presence can aid in correctly diagnosing scalp DLE alone or in conjunction with other described dermoscopic features such as follicular red dots, blue-grey dots, white patches, reduced follicular ostia, and absence of pinpoint white dots [Table 1]. In conclusion, trichoscopy is critical for diagnosing hair disorders and recognition of follicular keratotic plugging in DLE can lead to timely diagnosis and initiation of treatment.

Table 1

Dermoscopic features scalp DLE[2–5]