lichen planus ( lp ) is a common inflammatory disease affecting the skin , the mucous membranes , the genitalia , the nails and the scalp .
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 .
pathophysiology 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 .
several factors have been suggested as possible antigens , including viruses , bacterials and drugs .
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 .
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 , bullous , erythrodermic , inverse , linear , follicular , pemphigoides , pigmentosus , follicularis decalvans and actinic lp .
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 .
dermoscopy allows the visualization of structures located in the epidermis , dermo - epidermal junction and papillary dermis that can not be seen with the naked eye .
, cumulative evidence suggests that dermoscopy is also meaningful for the evaluation of inflammatory and infectious skin disorders . in the field of papulosquamous dermatoses
, dermoscopy has been shown to enhance the differential diagnosis among psoriasis , dermatitis , lp and pityriasis rosea . particularly for lp ,
dermoscopy brought to light that white crossing lines do not characterize only mucosal lesions , but cover virtually every cutaneous papule of active lp . in this report
we present a characteristic example of a patient with misleading clinical manifestations of lp resembling psoriasis .
a 61-year - old woman visited our department for evaluation of a three - month , mildly pruritic eruption on the soles and 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 erosive plaques on the soles .
. 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 figure 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 .
in the current case , clinical manifestations on the dorsal hands and plantar surfaces were highly suggestive of psoriasis , with eczema and lp included in the differential diagnosis .
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 .
although the presence of irregularly arranged dotted vessels and yellow scales were compatible with eczema , the prevailing dermoscopic features were the white crossing lines , corresponding to the so - called wickham striae , which is known as a highly specific criterion of lp .
clinical examination is undoubtedly the cornerstone of diagnosis in everyday dermatology practice , and in the majority of our patients , the macroscopic morphology is already enough to establish an accurate diagnosis .
this is especially true for widespread inflammatory diseases , where the combination of clinical history , morphology and distribution often points towards a specific diagnosis .
however , equivocal clinical manifestations do exist in everyday practice , posing diagnostic doubts and often prompting clinicians to perform diagnostic biopsies .
it has been demonstrated that coupling clinical examination with dermoscopy significantly improves the diagnostic performance of clinicians .
however , in order to maximize the benefit from dermoscopy in differentiation of inflammatory dermatoses , clinicians have to virtually use their dermatoscope on every lesion . in daily routine
furthermore , as shown in the current case , it may change our diagnostic thoughts , saving us from misdiagnosis and potential inappropriate management .
 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 established 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 . 
Introduction
Clinical presentation
Discussion