Severe flagellate erythema in idiopathic dermatomyositis

Description

A 32-year-old Caucasian female patient, with no previous or current health conditions, presented to our department with a 2-week history of acute proximal muscle weakness with extreme difficulty to walk, stand up or lift her arms. She also presented an important face and neck erythema along with erythematous lesions on her forearms, knees and thighs.

Physical examination revealed a heliotrope rash, a Shawl sign, Gottron’s papules and violaceous papular lesions on the forearms and knees. She also presented very painful erythematous and violaceous linear streaks on the outer side of the hips and thighs with superficial excoriations (figure 1). Neuromuscular examination revealed symmetrical muscle fatigue prominently in proximal muscles.

Figure 1.

Flagellate erythema on the hip and thighs.

Laboratory tests showed abnormally high muscle enzyme levels: creatinine phosphokinase (CPK)=3134 UI/L (15×N) and aldolase=25.4 UI/L (3×N). Electromyography revealed proximal myopathy and muscle biopsy showed muscle necrosis with perivascular inflammatory infiltrate. All these elements were consistent with the diagnosis of dermatomyositis. Further investigations, including a body scan and digestive endoscopy and nasoscopy, were performed revealing no signs of any associated neoplasm.

We concluded to an idiopathic dermatomyositis and the patient was treated with systemic corticosteroids 1 mg/kg/day and methotrexate 25 mg/week with resolution of the skin and muscular symptoms including the flagellate erythema in few weeks.

Flagellate dermatoses are defined by linear and parallel erythematous or pigmented streaks spontaneously appearing on the skin. Flagellate erythema was described for the first time in 1970 in patients treated with bleomycin.¹ It was later reported as a symptom that affects about 5% dermatomyositis patients. Its presence seems to be correlated with the disease activity and paraneoplastic aetiology.² A flagellate dermatitis was also described as a side effect after consumption of raw or unwell-cooked shiitake mushrooms.³

Flagellate erythema in dermatomyositis is mostly localised on the trunk and proximal extremities generally associated with pain or itching.⁴ It clinically manifests as reddish lines or streaks on the skin, whereas the lines in bleomycin-induced flagellate erythema are generally brownish and less inflammatory as they are mainly due to an increased density of melanosomes in keratinocytes.

Pathogenesis of flagellate erythema remains uncertain, but it has been suggested that minor injuries or trauma or recurrent stimuli by scratching can be in cause. It usually disappears spontaneously or with corticosteroid treatment.^{2 5}

Learning points.

• Flagellate erythema is a non-specific dermatological sign that can be seen in many medical conditions.

• Flagellate erythema is rarely seen in idiopathic dermatomyositis.

• It can be considered as an indicator of disease activity and possible association to a neoplasm.