the infestation occurs in all geografic areas , all age groups , races and social classes . poor economical conditions , and lack of proper hygiene are risk factors for the disease ( 1 , 2 ) . scabies is transmitted by close physical contact . main symptom is intensive pruritus which worsens in the night or in the conditions where the body temperature is raised . crusted scabies is a rare , highly contagious uncommon form of scabies which is characterized by presence of huge number of sarcoptes scabiei in the horny layer of the epidermis . as a reaction , the horny layer thickens and forms warty crusts ( 3 ) . in most cases it is associated with some underlying diseases and usually affects immunocompromised patients ( 4 - 7 ) . also , the host response can be modified by immunosuppressive therapy ( 8 , 9 ) . topical or systemic use of corticosteroids may mask the clinical picture of scabies and lead to another uncommon presentation - scabies incognito ( 10 , 11 ) , which can easily be mistaken for other skin diseases . the patient is 62-yr - old woman with skin changes which started 3 yr ago with diffuse erythematous , slightly infiltrated plaques on her trunk and extremities , with no clear borders , associated with moderate pruritus . because she had been suffered from hypothyroidosis for 20 yr , at the first dermatological examination , she was misdiagnosed and her skin changes were thought to be in relation with the endocrine disorder . first , she was treated with topical potent corticosteroids ( betametasone valerate 0.1% , triamcinolone acetonide 0.1% , fluocinonide 0.05% ) , in 1 to 2 weeks repeated courses , over five months , without effect . in next six months her skin changes became more extensive , erythrodermic with scaling and showed tendency for generalization , and then her diagnosis was erythroderma , also thought to be secondary to her hypothyreoidism . , she began with systemic corticosteroid therapy in medium doses ( 40 mg / day of prednisone ) . in first month of therapy her skin changes improved , and erythema and pruritus became less intensive , but every time with reduction of dose of steroids , she had an exacerbacion . sistemic corticosteroid therapy lasted almost one year with pauses and with doses between 20 and 40 mg of prednisone daily . biopsy specimens were taken several times , but on microscopic examination there were only signs of nonspecific inflammation . suddenly , she came to a hospital with widespread skin eruptions which had developed during previous few weeks . examination showed generalized erythema and scaling of the whole body and face with large hyperkeratotic plaques on her trunk and limbs and crusted lesions on her scalp and external ears ( fig . 1 , 2 ) . also , she had fever and raised body temperature . laboratory examination showed an elevated sedimentation rate ( 46 mm ) and leukocgtosis with eosinophilia ( 1.310/l ) . the haematologic ( urea , creatinine , hepatic enzimes , glukose level ) and urine analyses were normal . crusted scabies was suspected and microscopical examination of scrapings from the hyperkeratotic lesions from trunk ( we did not examined tips of fingers and toes ) showed numerous mites and eggs ( fig . she was treated first with 1% lindane ( one application , left on skin 24 hr ) with remarkable improvement . after treatment no live mites were found on microscopic examination , but after three days we repeated antiscabiotic treatment first with 25% benzyl benzoat and then with 10% precipitated sulphur ointment ( for three consecutive days ) . at the follow up controls after one , three and six months she had no signs of skin disease . maybe the reason of these serious infection is that patient lives in poor hygiene and socioeconomic conditions , she lives alone , without any human care . there had been outbreak of scabies among the staff ( 2 doctors , 5 nurses ) , and 14 patients who were in clinic in the same time . in the current scabies epidemic , when this infestation could be a global problem , esspecially in the developing countries and when it is estimated that about 300 million people is infested ( 12 ) , classic and typical clinical pictures of scabies became less frequently seen . on the contrary , crusted scabies was a rare form which was seen mostly in immunocompromised and mentally debilitated patients . with increasing use of different immunosuppressive therapies and increasing number of hiv patients , diagnosis of crusted scabies is not so rare as it was in the past . to date more than 200 cases have been reported ( 13 ) . the first patient with crusted scabies was described in 1848 , and in 1973 the first case attributable to therapy with immunosuppressive drugs was reported ( 8) . there are reports of crusted scabies after locally applied corticosteroids ( 14 ) , but it has also been seen in patients with normal immune response ( 15 ) . clinically , crusted scabies is a hyperkeratotic skin disease resembling psoriasis , but variable degree of erythema may be usual and it could generalize to erythroderma ( 13 , 16 ) . one of the problems of giving correct diagnosis is that among general practitioners it is usually a very low level of suspicion of this disease . the diagnosis of scabies always should be considered in patients with advanced malignancies and associated pruritus . also , this form of scabies may be a complication of immunosuppressant therapy and it may appear in immunocompromised patients , as in patients with prolonged use of corticosteroids , both topically and systemically , as in our patient . we think our patient almost certainly had scabies incognito at the first time she visited dermatologist , when she was misdiagnosed as having a skin condition like eczema secondary to her hypothyroidism . it might be that the first clinical appearance of skin changes was uncommon because of her underlying disease . after that , she was treated continuously about two years with corticosteroids , both topically ( betametasone valerate 0.1% , triamcinolone acetonide 0.1% , fluocinonide 0.05% ) and systemic ( 20 - 40 mg of prednisolone daily ) with little improvement , and the pruritus was persistent almost all the time . it is known that locally applied corticosteroids alter the skin immune system , the inflammatory response is reduced and the cellular immune response is suppressed ( 17 ) . the fact that until then , after antiscabiotic therapy , one year later , she is without skin changes , suggest that she had scabies all along . in view of its contagious nature physicians should be aware of the possibility of development crusted scabies in a patient who develops widespread hyperkeratotic eruptions . so , we could say that nowadays this diagnosis become challenge for the both general practitioners and dermatologists . it is very important to make a correct dignosis of crusted scabies , because misdiagnosis could be associated with serious consequences such as spreading of the infestation and superinfection of the lesions ( 18 ) , inducing sometimes life - threatening consequences .
it is a case study of a 62-yr - old female with crusted ( norwegian ) scabies , which appeared during her treatment with systemic and topical corticosteroid therapy , under the diagnosis of erythroderma . in the same time 
 , the patient had been suffered from hypothyoidism , and her skin changes were misdiagnosed , because it was thought that they are associated with her endocrine disorder . suddenly , beside the erythema , her skin became hyperkeratotic , with widespread scaling over the trunk and limbs , and crusted lesions appeared on her scalp and ears . 
 the microscopic examination of the skin scales with potassium hydroxide demonstrated numerous scabies mites and eggs . 
 repeated topical treatments with lindan , benzoyl benzoat and 10% precipitated sulphur ointment led to the complete resolution of her skin condition .