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Paper text:
lichen planus ( lp ) and lichen sclerosus ( ls ) share similar pathological and clinical features .
there have been a few reported cases in the literature of the coexistence of lp and ls .
we report a case of ls with cutaneous distribution simulating lp . a 31-year - old woman presented with a 1-year history of a severe pruritic eruption that initially developed on the dorsum of the feet and posteriorly also appeared on the neck , upper back and wrists ( fig . 1 , fig .
2 ) . exploration revealed small , centrally depressed , polygonal macular lesions on the wrists and dorsum of the feet .
the distribution of the lesions was bilateral and symmetrical . moreover , multiple atrophic papules of pearly coloration , bright and 5 - 8 mm in size on the neck and upper back were present .
there were no lesions affecting the oral mucosa , genitals , or rest of the body .
laboratory studies including hemogram , biochemistry , antibodies against thyroid and antinuclear antibodies , and borrelia , hepatitis b and c virus serology were within normal ranges or were negative .
the histopathologic study of two wrist and back lesions showed an atrophic epidermis , homogenization of the upper dermis and a mid - dermal lymphocytic infiltrate , consistent with lichen sclerosus et atrophicus ( fig .
the patient was diagnosed as ls simulating a distribution of lp , and topical corticosteroid treatment produced a clear improvement of the lesions .
lp and ls share several common features , including lymphocytic infiltration at the dermal - epidermal junction , clinical involvement of both skin and mucosa , erosive disease of mucosal surfaces , and the occasional occurrence of squamous cell carcinoma at the site of chronic , erosive mucosal lesions .
there are only rare reports of concurrent lp and ls , but the number of reported cases of ls with lp - like distribution is even lower .
cases have been reported of simultaneous ls and localized scleroderma ( morphea ) in the same patient and even within the same lesion [ 2 , 3 ] .
different authors have suggested that both processes ( ls and lp ) are part of a clinical spectrum . a parallel exists between lp / ls and graft - versus - host disease ( gvhd ) , where in early chronic gvhd
it is therefore tempting to speculate on the immunological relationship between lp and ls [ 3 , 4 ] . in ls and lp , there is a strong dermal inflammatory infiltrate comprised of t lymphocytes . in ls , a specific t - cell response to bp180 , a structural protein of the basement membrane zone , has been demonstrated .
the demonstration of the presence of circulating autoantibodies to extracellular matrix protein and to basement membrane zone ( bmz ) components , chiefly bp180 , suggests that autoimmunity to these components might contribute to pathogenesis [ 5 , 6 ] .
this contrasts with lp and cutaneous ls which , for the moment , have not been shown to be associated with an autoimmune disorder . in spite of clinical and histological similarities and possible common immunological origin ,
there are a few cases of concurrence of ls and lp , and ls simulating lp .
we report a new case of ls with a typical distribution of lp in a young woman .
lichen sclerosus ( ls ) et atrophicus is a disease of unknown etiology , although hereditary , endocrine , and autoimmune factors are known to be involved . while the anal and genital regions are predominantly affected , only 2.5% of patients present with extragenital lesions , particularly of the trunk , neck , and upper limbs . 
 the possible relationship between lichen sclerosus et atrophicus and both lichen planus ( lp ) and localized scleroderma ( morphea ) has not been clearly established , although in a number of cases , several of these conditions have been found simultaneously . 
 we report the case of a 31-year - old woman with ls lesions affecting the neck , upper back , wrist and dorsum of the feet . 
 the unusual character of this presentation is pointed out , along with its clinical similarity to lp .