Dermoscopic Features of Psoriasis, Lichen Planus, and Pityriasis Rosea in Patients With Skin Type IV and Darker Attending the Regional Dermatology Training Centre in Northern Tanzania

Background Papulosquamous skin diseases can be challenging to diagnose, especially in dark skin. Dermoscopy is reported to be helpful, but few data are available on its use in skin type IV or darker. Objective To describe dermoscopic features in plaque-type psoriasis (PP), lichen planus (LP), and pityriasis rosea (PR) patients attending the Regional Dermatology Training Centre in Moshi, Northern Tanzania, and to compare findings with published data. Methods A descriptive cross-sectional study was conducted at a tertiary hospital from October 2016 to June 2017. Fifty-six patients with PP, 25 with LP, and 9 with PR were enrolled consecutively. Clinical diagnosis was confirmed with histopathology in 74.4%. Dermoscopic vascular and nonvascular features from 225 lesions were analyzed. Results Of the 90 patients enrolled, 58.9% were male and the median age was 50 (interquartile range 32.8–60.0) years. In PP lesions, red dots were found in 64.2% and white scale in 45.5%. In LP lesions the background was violet in 45.5% and 58.2% revealed Wickham striae. In PR lesions a dull red background was found in 50.0%, white scale in 83.3%, but no vessels were detectable. Conclusion Dermoscopy features in PP, LP, and PR in dark skin are mostly similar to those in light skin.

. The NO treatment group was defined as no topical treatment in the last 4 weeks or none at all; no systemic treatment was defined as no systemic corticosteroids in the last 4 weeks, no methotrexate in the last 3 months, or no systemic treatment at all [6,8]. Patients who had mucous membrane or nail lesions only, and those with atypical clinical appearance and refused biopsy, were excluded. Patient characteristics included sex, age, diagnosis, treatment status, anatomical site, Fitzpatrick skin type [12], and lesion morphology. The skin color was assessed at a non-sunexposed area (right upper medial arm).

Results
Ninety patients were enrolled (58.9% men and 41.1% women). The median age was 50 years (IQR 32.  In patients with PP, 148 lesions were assessed. The majority of the lesions (64.2%) were from the trunk and limbs, followed by elbows/knees (15.3%), scalp (13.5%), palmoplantar (8.8%), face (7.4%), and intertriginous sites (6.1%). In the patients with LP, 55 lesions were examined and the majority (67.3%) were from the trunk or limbs. In the PR patients, 54.5% of the 22 lesions were located on the trunk and limbs.

Dermoscopic Features in PP
The most common features of the 148 PP lesions were light red background (43.9%), red dotted vessels (64.2%), regu-

Introduction and Background
Plaque-type psoriasis (PP), lichen planus (LP), and pityriasis rosea (PR) are common skin diseases and may have a negative impact on quality of life [1]. The clinical diagnosis can be challenging; sometimes a biopsy is needed, thus delaying the diagnosis and correct treatment [2]. Moreover, erythema often observed in these papulosquamous conditions may be masked in a dark-skin population [3,4]. In general, misdiagnosis is reported in up to 32% of papulosquamous diseases but may be even higher in patients with dark skin [5].
Dermoscopy as a noninvasive diagnostic tool can help to diagnose without the need of a biopsy [6]. However, few data are available so far about its use and impact in inflammatory skin diseases in patients with skin type IV or darker [6].
Published data about dermoscopy on inflammatory lesions, so-called inflammoscopy, is mainly from countries with Caucasian or Asian patients, but only a few articles describe their patients' skin type [7,8]. Thus, there is little knowledge regarding dermoscopic features in papulosquamous conditions in patients with dark skin (Fitzpatrick IV or darker) so far. A higher degree of dyspigmentation and less noticeable erythema has been described in psoriasis lesions in dark skin because of poorly visible dermal vessels [4,6]. In LP, a violaceous color is helpful as a diagnostic feature in lighter skin but it is less visible in darker skin, and therefore it is still not evident whether dermoscopy could be helpful here [9].
The aim of this descriptive study was to describe dermo-

Methods
This hospital (tertiary)-based descriptive cross-sectional study was conducted at the Regional Dermatology Train-  Table 2).

Dermoscopic Features in LP
Also, none of the papules had scales.
White scales were observed in 80.0% of patches (n = 4) and 55.6% of plaques

Discussion
Dermoscopic features in PP, LP, and PR were observed to differ between these skin diseases in patients with skin type IV and darker (Table 5). Compared to the literature, these findings were mostly similar to lighter skin types (I-III) (Figure 1, D-F), but in lower frequencies.
Among patients with PP, red dots were seen in 64.2% of lesions in contrast to Lallas et al [7], who described them in 97.1% ( Figure 1E) Figure 1C).

Dermoscopic Features in PR
The  in our study and 85% by Lallas et al [6]), but in our patients patchy and peripheral distribution were in equal more dull/dark red in dark skin (Figure 1C). Perhaps due to the dark pigmentation, we observed no vessels, in contrast to Lallas et al, who reported red dots in 100% of their patients [6].
not surprising as plaques are expected to be more active.
We noted nonvascular features as seen in Figure 1B to be more common in LP, in agreement with literature reports.
A pearly white background (PWS) was the most common finding, in 58.2%, and this is similar to the 60% described by Chandravathi and colleagues [8]. PWS were also more often detectable in the nontreated lesions [15]. In the nontreated group, PWS were seen more in papules and plaques compared to patches, and this is expected as PWS correspond to compact orthokeratosis over areas of hypergranulosis and acanthosis [16].  [17]. In the NO treatment group, the violaceous color was seen more in raised lesions compared to patches, and this is expected as papules and plaques are expected to be more active in LP.
Follicular changes were some of the less observed findings, with comedolike openings at 16.4% similar to the 20% reported by Garg et al [18]. Pigmentary changes were seen in 69.1% of lesions, and this could be related to more pigmentation in dark skin [9].
PWS are reported to be the most helpful dermoscopic feature in diagnosing LP, especially in untreated patients [6]. Our study confirms this observation in skin type IV and darker.
In PR lesions the most common background color in our study was dull red (50%) compared to yellow (65%) among Caucasian patients, as reported by Lallas and colleagues [6].
This observation supports the idea that erythema could have various presentations based on pigmentation, ie, more yellowish in light skin ( Figure 1F) and

Recommendations
Further studies, probably with high-res-