cutaneous lupus erythematosus ( cle ) is an autoimmune disease characterised by a wide spectrum of skin lesions that typically occur on sun - exposed areas of the skin . in addition to the classical forms of cle , which include discoid lupus erythematosus and subacute cutaneous lupus erythematosus ( scle ) , there are uncommon subsets and atypical clinical variants , which may be diagnostically challenging.1 furthermore , different forms of cutaneous lupus may be induced by various drugs . drug - induced scle has been associated with common systemic medications such as hydrochlorothiazide , calcium channel blockers , angiotensin - converting enzyme inhibitors , proton pump inhibitors , tumour necrosis factor ( tnf)- inhibitors , chemotherapy agents and terbinafine.13 we report the case of a foot masseuse with an unusual presentation of scle isolated to the dorsum of the hands and interdigital spaces . we propose that occupation as a foot masseuse may have predisposed the patient to sensitisation to topical terbinafine and may explain the patient 's condition . an otherwise healthy foot masseuse presented to the dermatology clinic at bellevue hospital center with a chief complaint of hand lesions for 2  months , associated with skin peeling and itchiness . the patient had no other medical complaints , no significant medical history and was on no other medications . the patient reported working as a foot masseuse for many years and admitted to regularly applying topical terbinafine to the clients ' feet without gloves . physical examination revealed well - demarcated , scaling , erythematous plaques with hyperpigmented borders and some erosive , indurated plaques interdigitally and on the dorsum of the hands ( figure 1 ) . no similar lesions were found elsewhere on the body . a potassium hydroxide ( koh ) was negative , and the patient 's hand dermatitis was treated as a contact dermatitis with clobetasol 0.05% ointment . on return visit 1 month later two skin biopsies were then performed on the left fourth digit and left dorsal hand . histopathology of both skin biopsies revealed superficial and deep perivascular , periadnexal and band - like infiltrate comprised of lymphocytes , histiocytes and rare plasma cells . lymphocytes extended to the overlying , slightly hyperplastic epidermis with vacuolar changes , numerous necrotic keratinocytes and hyperkeratosis with foci of parakeratosis . a periodic acid - schiff ( pas)-d stain revealed slight thickening of the basement membrane and no evidence of fungal hyphae . a colloidal iron stain revealed increased deposits of connective tissue mucin throughout the dermis , most prominent in the reticular dermis . these findings were most consistent with a connective tissue disease such as discoid lupus or scle . ( a ) topical terbinafine - induced subacute cutaneous lupus erythematosus ( scle ) stain revealed hyperkeratosis , superficial and deep perivascular lymphohistiocytic infiltrate , vacuolar changes and deposits of connective tissue mucin in dermis . colloidal iron stain revealed increased deposits of connective tissue mucin throughout the dermis , most prominent in the reticular dermis . laboratory evaluation performed after biopsy revealed normal complete blood count , kidney function , hepatic panel and urinalysis . ana was positive in a speckled pattern at a titre of 1:40 , anti - anti - sjgren 's syndrome type a ( ssa)/ro antibody was positive at 1.6 antibody index ( ai ) and anti - anti - sjgren 's syndrome type b ( ssb)/la antibody was negative . based on the clinical history , physical examination , histopathology and serology , the diagnosis of acral scle was made . after discontinuation of topical terbinafine , the lesions gradually resolved , and on telephone follow - up 6  months later there has been no further recurrence of the illness . cle is a highly photosensitive condition that usually affects sun - exposed areas of the face and scalp.1 it does not commonly affect the hands in isolation without any other lesions in more photosensitive areas of the body . a literature search disclosed many reports on cle and involvement of acral surfaces , none of which described this rare and atypical clinical presentation of isolated dorsal and interdigital scle.4 
 5 of those cases reported in the literature , the majority presented with discoid lesions.4 
 5 our patient had primarily scaly , erythematous lesions of the fingers and interdigital spaces that were clinically most consistent with scle and supported by positive speckled ana and positive anti - ssa / ro antibodies.1 
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 7 scle may be induced by various oral medications , most commonly antihypertensive agents and oral terbinafine.2 one study found that patients with drug - induced scle were older , had more extensive skin involvement and had an increased incidence of bullous , erythema multiforme - like and vasculitic lesions compared with individuals with idiopathic scle.7 photodistribution is characteristic as in our patient , and resolution occurred within a few months without treatment as noted in the literature.8 interestingly , our patient 's unusual presentation of localised scle lesions on the hands may be explained by an occupational exposure to a topical drug , namely terbinafine . as a foot masseuse systemic administration of this agent is a well - known cause of drug - induced scle , but there are no reports of topical induction of scle.1 
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 9 terbinafine is an allylamine with antimycotic effects that is used in the treatment of fungal foot and nail infections.10 it is a highly lipophilic substance that may concentrate in the skin , nails and fatty tissue for a prolonged period of time10 while topical terbinafine is not readily absorbed into the systemic circulation and therefore would unlikely cause systemic lupus flare , the possibility arises that if locally absorbed it may induce focal development of scle10 studies have demonstrated that the average incubation time for terbinafine - induced scle was 5.1  weeks ( range 112  weeks).6 
 9 our patient 's initial lesions on the dorsal hand and interdigital spaces may have resulted from prolonged exposure to topical terbinafine . our patient 's cutaneous manifestation of scle on the hands is noteworthy because of the sparing of the palmar surfaces . in an occupational exposure as a foot masseuse one possible explanation is that the thickness of the palmar surface of the hand limited the permeability of topical terbinafine , as opposed to the thinner skin on the dorsum of the hand . studies have shown that skin permeability is variable in different areas of the body , being generally greatest in thin - skinned surfaces.11 another explanation for involvement of the dorsum of the hand versus the palmar surface is increased exposure to ambient ultraviolet ( uv ) radiation . whether the uv radiation , medication or a combination of these exogenous factors precipitated the patient 's condition is not clear . genetics have been shown to play an important role in the development of scle , specifically in individuals with human leucocyte antigen ( hla ) b8 , hla - dr3 , hla - drw52 and hla - dq1.12 it is speculated that uv radiation stimulates keratinocytes and dermal fibroblasts to release cytokines such as tnf- and interleukins involved in immunomodulation and apoptotic pathways in scle.13 in addition , nuclear antigens ( including anti - ssa / ro ) in keratinocytes that have been translocated to the cell surface may be targeted by circulating anti - ssa / ro antibodies and cytotoxic t cells.7 
 13 in drug - induced scle , the induction of a photosensitivity state by certain medications may induce skin lesions via an isomorphic ( kebner ) response in predisposed individuals.2 terbinafine is capable of producing a photosensitivity state and is speculated to induce scle through this mechanism.2 the pathogenesis of drug - induced scle may vary according to individual medications.2 for example , hydrochlorothiazide is hypothesised to enhance the cytotoxicity of anti - ro antibodies and induce epidermal cytotoxicity through direct phototoxicity.3 this case represents a rare and interesting instance of scle isolated to the dorsum of the hand and interdigital spaces . we propose that localised exposure of the hands to topical terbinafine in an occupational setting was the cause of this unusual presentation . although little is known about the absorption and pharmacodynamics of topical terbinafine , its potential to induce scle topically deserves further investigation .
subacute cutaneous lupus erythematosus ( scle ) is a well - defined subtype of lupus erythematosus , characterised by photosensitivity , annular and/or psoriasiform lesions , variable systemic involvement and presence of circulating ssa / anti - ro antibodies . 
 scle may be idiopathic or drug - induced . 
 both the idiopathic and drug - induced forms of scle are analogous in their clinical , serological and histological features . 
 drug - induced scle has been reported with various oral agents , but to our knowledge this is the first reported case due to a topical medication . 
 a 34-year - old female foot masseuse presented with a 2-month history of scaly , erythematous lesions isolated to the dorsal hands and interdigital spaces . 
 she had used topical terbinafine , a topical antifungal cream , to her clients feet for a number of years . 
 ana and anti - ssa / ro antibodies were positive . physical examination , serology and histopathology were consistent with scle . 
 we propose that our patient 's unique presentation of scle may be explained by a prolonged occupational exposure to topical terbinafine as a foot masseuse . 
 while oral terbinafine is a drug known to cause drug - induced scle , to our knowledge , this is the first topically induced form of the disease .