An Adolescent Patient with Scabies Mimicking Gottron Papules.

Atypical features of scabies occur in infants and children and patients with prolonged use of corticosteroids or immunosuppression. We report a non-immunosuppressed 15-year-old female case of scabies showing scaly reddish papules over the proximal interphalangeal joints mimicking Gottron papules in classic dermatomyositis. Periungal erythema was also seen. Four months' topical corticosteroids from previous clinics had been used. Dermoscopic findings were consistent with typical pictures of scabies. Scraping of hand crusts demonstrated scabies mites and ova. Skin lesions of the patient were cured with oral ivermectin and topical 10% crotamiton. This case suggests that a lesion resembling Gottron papules may be added to the panel of unusual presentations of scabies.

Introduction

Scabies is endemic in some poor tropical and subtropical areas as well as in selected communities, and it is sporadic in industrialized countries [1]. In order to prevent a scabies epidemic, dermatologists should know the unusual skin manifestations of scabies as well as typical lesions. We report here an adolescent case of scabies showing peculiar skin lesions mimicking Gottron papules.

Case Report

A non-immunosuppressed 15-year-old female outpatient was seen in June 2009 with a 4-month history of pruritic lesions on the hands, trunk and upper extremities that had been treated with topical corticosteroids given by previous clinics. She had no muscle pains or fatigue. There was no past history of atopic dermatitis or collagen diseases. Physical examination revealed dusky, red papules over the proximal interphalangeal joints (fig. 1) that suggested Gottron papules of classical dermatomyositis. There was periungal erythema (fig. 1) without nail fold telangiectasia. Numerous pruritic papules and scratch marks were seen on the trunk. Laboratory tests including blood cell count, biochemistry, and cell-mediated immunity were within normal ranges.

Fig. 1

Scaly reddish papules over the proximal interphalangeal joints resembling Gottron papules. Periungal erythema without nail fold telangiectasia was seen.

Dermoscopic findings at ×25 showed characteristic triangular shapes, burrows and scale crusts (fig. 2a), consistent with typical pictures [2]. Potassium hydroxide (KOH) examination of scales and papules from the hands showed mites and eggs (fig. 2b). The patient was administered an oral dose of 200 μg/kg ivermectin twice with topical 10% crotamiton ointment. The skin lesions had resolved 2 months later. Her 40-year-old mother and 12-year-old brother were seen with pruritic papules on the trunk and upper extremities where mites and eggs were found. Two months’ therapy with topical 10% crotamiton led to a cure.

Fig. 2

a Dermoscopic findings of multiple scabies burrows and mites. b Scabies mites and ova from scraping of hand crusts.

Discussion

Classic scabies is characterized with small erythematous papulovesicular rash, papules, erosion due to scratching, burrows, and nodules [3]. These findings have a predilection for anterior axillary folds, nipple area, periumbilical skin, elbows, volar surface of the wrists, interdigital webspaces, belt line, thighs, buttocks, penis, scrotum, and ankles [3]. Scabies often affects the face, head, neck, scalp, palms, and soles in infants and young children [4], whereas involvement of the dorsum of the fingers is rare both in adults and children. Nodular scabies, scabies incognito, and bullous scabies are known as uncommon presentations [5]. Gottron papules are considered to be pathognomonic of dermatomyositis [6]. However, Gottron-papules-like lesions shown in our patient have not been reported as a manifestation of scabies. Atypical features of scabies frequently occur in infants and children and patients with prolonged use of corticosteroids or immunosuppression. Unusual skin lesions in our adolescent patient may have been caused by 4-month use of corticosteroids. Our case suggests that a lesion resembling Gottron papules may be added to the panel of atypical presentations of scabies.