Dermatology: Practical and Conceptual Observation | Dermatol Pract Concept 2016;6(4):9 39 DERMATOLOGY PRACTICAL & CONCEPTUAL www.derm101.com Introduction Lichen planus (LP) is a common inflammatory disease affect- ing the skin, the mucous membranes, the genitalia, the nails and the scalp [1]. Prevalence of lichen planus in the general population ranges from 0.1 to 4 % and it is more common in females, especially in the perimenopausal period [1,2]. Patho- physiology of LP involves an immune-mediated reaction, in which an antigen is processed to T-lymphocytes and they, subsequently, attack basal keratinocytes, leading to apoptosis of the cells [3]. Several factors have been suggested as possible antigens, including viruses, bacterials and drugs [3,4]. The typical clinical manifestations of LP are purple to violaceous polygonal papules with sharp borders, usually pruritic, most commonly developing on the extremities and the trunk. Less frequently the disease affects the genital area, mucous membranes, palms and soles and nails [1,5]. Mucosal lesions are typified by the presence of reticular white lines, known as Wickham striae. The disorder has several clinical variations: annular, hypertrophic, atrophic, ulcerative, bul- lous, erythrodermic, inverse, linear, follicular, pemphigoides, pigmentosus, follicularis decalvans and actinic LP [3]. The diagnosis of LP is usually established clinically based on the characteristic morphology of the lesions and the coexisting intense pruritus. However, atypical presentations requiring histopathologic confirmation of the diagnosis do exist [1]. Dermoscopy allows the visualization of structures located in the epidermis, dermo-epidermal junction and papillary dermis that cannot be seen with the naked eye [6]. Initially, dermoscopy was almost exclusively used to evaluate skin Atypical case of lichen planus recognized by dermoscopy Chrysoula Papageorgiou1, Zoe Apalla1, Elizabeth Lazaridou1, Elena Sotiriou1, Efstratios Vakirlis1, Demetrios Ioannides1, Aimilios Lallas1 1 First Department of Dermatology, Aristotle University, Thessaloniki, Greece Key words: lichen planus; dermoscopy; psoriasis; Wickham striae; eczema Citation: Papageorgious C, Apalla Z, Lazaridou E, Sotiriou E, Vakirlis E, Ioannides D, Lallas A. Atypical case of lichen planus recognized by dermoscopy. Dermatol Pract Concept 2016;6(4):9. doi: 10.5826/dpc.0604a09 Received: August 8, 2016; Accepted: August 23, 2016; Published: October 31, 2016 Copyright: ©2016 Papageorgiou et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: None. Competing interests: The authors have no conflicts of interest to disclose. All authors have contributed significantly to this publication. Corresponding author: Chrysoula Papageorgiou, MD, First Department of Dermatology, Aristotle University, Thessaloniki, 124 Delfon Str, 54643, Thessaloniki, Greece. Tel.: 00302313308882; Fax: 00302310277979. Email: xrysapapageorgiou@gmail.com Lichen planus (LP) is an inflammatory disease that affects the skin—mainly the extremities and the trunk—the mucous membranes, the genitalia, the nails and the scalp. The diagnosis of LP is usually es- tablished clinically based on the typical morphology and distribution of the lesions in conjunction with the associated itch. We report a patient with LP manifesting highly psoriasiform lesions, that could only be correctly assessed after the application of dermoscopy, which revealed LP-specific findings. ABSTRACT mailto:xrysapapageorgiou@gmail.com 40 Observation | Dermatol Pract Concept 2016;6(4):9 the dorsal surfaces of the feet and hands. Clinical examination revealed hyperkeratotic plaques on the dorsal surface of the feet and hands and erythematous hyperkeratotic, partially ero- sive plaques on the soles. As shown in Figure 1, the overall clini- cal presentation was highly suggestive of psoriasis. Surprisingly, application of dermoscopy did not reveal the expected psoriatic pattern of regularly distributed dotted vessels and white scales (Figure 2). Instead, white crossing lines (the so-called Wickham striae) were dermoscopically evident, along with dotted and short linear vessels and yellow scales. Since the dermoscopic presence of Wickham striae is considered highly specific of LP, the dermoscopic findings prompted us to perform a biopsy for histopathologic assessment. Histopathology, as shown in Fig- ure 3, revealed hyperkeratosis, dense hypergranulosis, vacuolar degeneration of basal cell keratinocytes, band-like lymphocytic infiltration in the upper dermis, as well as presence of colloid bodies, justifying the diagnosis of LP. tumors [7,8]. However, cumulative evidence suggests that dermoscopy is also meaningful for the evaluation of inflam- matory and infectious skin disorders [7,9]. In the field of papulosquamous dermatoses, dermoscopy has been shown to enhance the differential diagnosis among psoriasis, dermatitis, LP and pityriasis rosea [7,10]. Particularly for LP, dermoscopy brought to light that white crossing lines do not characterize only mucosal lesions, but cover virtually every cutaneous pap- ule of active LP [7]. In this report we present a characteristic example of a patient with misleading clinical manifestations of LP resembling psoriasis. Application of dermoscopy was the key point guiding to the accurate diagnosis [11]. Clinical presentation A 61-year-old woman visited our department for evaluation of a three-month, mildly pruritic eruption on the soles and Figure 1. Lichen planus. Erythematous plaques covered by silvery-whitish scales. Both the clinical morphology and the distribution of the skin lesions are indicative of psoriasis. [Copyright: ©2016 Papageorgiou et al.] Observation | Dermatol Pract Concept 2016;6(4):9 41 arranged dotted vessels and yellow scales were compatible with eczema [7,14,15], the prevailing dermoscopic features were the white crossing lines, corresponding to the so-called Wickham striae, which is known as a highly spe- cific criterion of LP [7,10,11]. Clinical examination is undoubtedly the cornerstone of diagnosis in everyday dermatology practice, and in the major- ity of our patients, the macroscopic morphology is already enough to estab- lish an accurate diagnosis. This is espe- cially true for widespread inflammatory diseases, where the combination of clini- Discussion In the current case, clinical manifes- tations on the dorsal hands and plan- tar surfaces were highly suggestive of psoriasis, with eczema and LP included in the differential diagnosis. However, application of dermoscopy significantly influenced our diagnostic thoughts. This was because the lesion deviated from the standard dermoscopic pattern of psoriatic lesions, which are composed of regularly distributed dotted vessels and white-colored scales [7,12,13]. Although the presence of irregularly Figure 2. Lichen planus. Dermoscopy revealed dotted and short linear vessels and yellowish scales. However, the most prominent dermoscopic finding are the white crossing lines (Wick- ham striae). [Copyright: ©2016 Papageorgiou et al.] cal history, morphology and distribution often points towards a specific diagnosis [14]. LP and psoriasis are two charac- teristic examples, representing entities routinely diagnosed straightforward. However, equivocal clinical manifesta- tions do exist in everyday practice, pos- ing diagnostic doubts and often prompt- ing clinicians to perform diagnostic biopsies [12]. It has been demonstrated that coupling clinical examination with dermoscopy significantly improves the diagnostic performance of clinicians [7]. However, in order to maximize the benefit from dermoscopy in differen- tiation of inflammatory dermatoses, clinicians have to virtually use their dermatoscope on every lesion. In daily routine, dermoscopy often confirms and strengthens our clinical suspicion. Fur- thermore, as shown in the current case, it may change our diagnostic thoughts, saving us from misdiagnosis and poten- tial inappropriate management. References 1. Usatine RP, Tinitigan M. Diagnosis and treatment of lichen planus. Am Fam Physician 2011;84(1):53-60. PMID: 21766756 2. 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