Dermatomyositis in Childhood

Lichenoid and interface dermatoses

The terms 'lichenoid' and 'interface' dermatitis are often used interchangeably to describe an inflammatory pattern characterized histologically by damage to the basal keratinocytes in the epidermis. The mechanism of cell damage of such cells is now best understood as apoptosis, or programmed cell death. This inflammatory pattern of dermatoses, is also accompanied frequently by a band of lymphocytes and histiocytes in the superficial dermis, that often obscures the dermal-epidermal junction, hence the term 'lichenoid'. A discussion of the more common lichenoid/interface dermatitides encountered in the routine clinical practice encompasses the following entities: lichen planus, lupus erythematosus, dermatomyositis, erythema multiforme, graft versus host disease, fixed drug reactions, and multiple others.

Analysis of gene transcript profiling and immunobiology in Shetland sheepdogs with dermatomyositis

Dermatomyositis (DM) is a canine and human inflammatory disease of the skin and muscle that is thought to be autoimmune in nature. In dogs, DM occurs most often in the rough collie and Shetland sheepdog. Characteristic skin lesions typically develop on the face, ears, tail, and distal extremities. The severity of lesions varies and is thought to increase with stressful stimuli. Previous studies in the collie suggest that DM is inherited in an autosomal dominant fashion with incomplete penetrance. The work presented here concerns gene transcripts profiling and immunobiology of DM in the Shetland sheepdog. Gene transcript profiles were generated for affected and normal skin using a canine-specific oligonucleotide array having 49,929 probe sets. Two-hundred and eight-five gene transcripts, many of which are involved in immune function, were found to be differentially regulated in these tissues. Also reported are Western blot, immunohistochemistry, and immunofluorescence analyses which showed that staining patterns with sera from normal and affected dogs are quite similar. While our work suggests that canine DM is a disease that may be immune mediated, it did not detect the production of specific disease-associated autoantibodies.

Dermatomyositis with a pityriasis rubra pilaris-like eruption: an uncommon cutaneous manifestation in dermatomyositis

A pityriasis rubra pilaris-like eruption has been described in patients with dermatomyositis. We describe an 11-year-old girl with dermatomyositis who had additional clinical findings of pityriasis rubra pilaris. Over a year, she developed muscle weakness, increasing fatigue, and a markedly elevated creatinine kinase level in addition to her cutaneous eruption and was seen in our clinic for these complaints. A year earlier, when a generalized, scaly erythematous eruption had appeared, she had been diagnosed as pityriasis rubra pilaris clinically and histopathologically. Dermatologic examination found scaling erythematous plaques involving the trunk and upper and lower extremities. Islands of unaffected skin were intermingled with erythematous plaques that were characteristic of pityriasis rubra pilaris. A skin biopsy specimen showed the findings of dermatomyositis and that diagnosis was made. The laboratory findings, electromyographic pattern, and muscle biopsy were also consistent with dermatomyositis. Her presentation is interesting, as she had been diagnosed as pityriasis rubra pilaris both clinically and histopathologically 1 year earlier and, although the cutaneous lesions had not changed, a diagnosis of dermatomyositis was made a year later.

Management of collagen vascular diseases in childhood

Collagen vascular diseases seen in children include systemic, discoid and neonatal lupus, dermatomyositis, scleroderma, juvenile rheumatoid arthritis, and, in rare cases, Sjogren's syndrome. Although these diseases are uncommon in children, when seen, they are associated with significant morbidity. This review describes the clinical features of each condition and provides an overview of treatment options now available. These include numerous systemic treatments which can be used as steroid-sparing agents.

Characteristics of juvenile dermatomyositis in Japan

Questionnaires were sent to 1290 hospitals in Japan asking for data on patients with juvenile dermatomyositis (JDM) diagnosed between June 1984 and May 1994. Of the 204 patients identified by these questionnaires, 102 met the criteria for JDM. JDM is categorized into three subtypes: Banker-type JDM, Brunsting-type and fulminant-type; patients with the latter exhibit markedly elevated serum levels of creatinine phosphokinase (> 10,000 U/mL) and appear to be at risk of renal failure. Cutaneous manifestations were present in 98% of patients and preceded the appearance of other symptoms. This tendency is one of the reasons for the difficulty in some cases in diagnosing the onset of JDM. Better criteria for early treatment of JDM are needed. The results of the present study suggest that itching and calcinosis are factors that indicate a poor prognosis in patients with JDM. Muscle enzyme levels do not always reflect disease activity, suggesting that methods other than measurement of muscle enzymes, such as measurement of the levels of neoprerin and von Willebrand factor antigen, as well as magnetic resonance imaging should be used to be evaluate disease severity. Patients with Brunsting-type JDM who exhibit dysphagia and antinuclear antibody positivity and patients with Banker-type JDM should be treated aggressively. Pulse therapy should be selected as the initial therapy in patients with fulminant-type JDM.

The role of microvascular injury in the pathogenesis of cutaneous lesions of dermatomyositis

Although microvascular injury has been postulated as the pathogenetic basis of skeletal muscle injury in dermatomyositis (DM), its role in the genesis of the skin lesions, which are said to be difficult to distinguish light microscopically from systemic lupus erythematosus (SLE) and subacute lupus erythematosus (SCLE), has not been analyzed. The authors' intention was to assess the role of microvascular injury in the pathogenesis of skin lesions in DM, SLE, and SCLE. Light microscopic features of biopsies of lesional skin from 20 patients with myopathic DM and 11 with amyopathic DM were compared to eight lesional skin biopsies from eight patients with SLE and 12 lesional skin biopsies from 12 patients with SCLE. Vascular density was compared in the three groups using an immunohistochemical preparation with an antibody to factor VIII. In 12 biopsies from the DM group, and in 19 of 20 lupus erythematosus (LE) specimens, frozen tissue was available. An indirect immunofluorescence methodology was used to detect C5b-9 deposition, and direct immunofluorescence studies for other immunoreactants were performed in standard fashion. Compared with LE, lesions of DM showed a greater degree of endothelial injury, vascular ectasia, and vascular fibrin deposition; there were no differences between myopathic versus amyopathic DM. C5b-9 deposition in vessels was significantly greater in DM than in LE. The superficial vascular plexus density was reduced in lesions of DM versus LE control groups with the greatest reduction observed in myopathic DM. Epithelial injury and mucin was greatest in myopathic DM. Microvascular injury is the apparent pathophysiological basis of skin lesions in DM. Careful attention to microvascular pathology enables distinction of DM from SLE and SCLE. Indirect immunofluorescence testing using a monoclonal antibody to C5b-9 is a valuable tool to distinguish DM from LE in biopsies of lesional skin.

Prognosis in juvenile dermatopolymyositis: a cooperative retrospective study of 70 cases

A retrospective multicenter study was conducted with 70 patients with juvenile dermatopolymyositis. Among survivors with sufficient follow-up (at least two years), a good prognosis subgroup was characterized by significantly better (P less than 0.001) initial response to steroids and less frequent pharyngeal involvement when compared to other patients in a poor prognosis subgroup with significant sequelae or still active disease. Patients who died had more severe pharyngeal involvement than those who survived (P less than 0.05).

Recurrent photosensitive dermatitis preceding juvenile dermatomyositis

The classic features of childhood dermatomyositis include muscle weakness, elevated muscle enzymes, and characteristic abnormal muscle biopsy and electromyography. Paramount to the diagnosis are cutaneous dermatoses that include a heliotrope rash and Gottron's papules. Rarely, a photo-sensitive dermatosis may occur. A recurrent photoexacerbated dermatoses can be an initial sign of occult childhood dermatomyositis.