Dermatomyositis in Childhood

The purpose of this paper is to describe four cases of dermatomyositis in children, which were seen in the Royal Aberdeen Hospital for Sick Children in the past five years. Though dermatomyositis is probably not an extremely rare disease, the number of cases previously reported, particularly in childhood, is not high, and the etiology and essential pathology are still obscure. Dermatomyositis may be defined as a disease process running, as a rule, a sub-acute or chronic course over a period of months or sometimes years, and characterized in childhood by pyrexia in the early stages, by skin rashes-frequently intermittent, commonly erythematous in type, and, in some cases, progressing to generalized scleroderma; by a firm oedema of the skin and subcutaneous tissues, especially of the malar regions and the extremities, and by pain, weakness, atrophy, and sometimes sclerosis of the limb muscles. From this picture, however, individual cases may show wide variations, particularly in the skin lesions, which may be urticarial, telangiectatic, erysipeloid, or purpuric in nature, and in the extent to which the brunt of the disease falls on the skin, the muscles, and the connective tissues. A number of cases have also been reported in which the mucous membranes have been involved. Most authors appear to agree with Langmead's view (1923) that dermatomyositis does not, by itself, constitute a disease entity, but falls into a group of conditions which includes also diffuse scleroderma, sclerodactyly, myositis fibrosa, and calcinosis universalis. Cases intermediate in symptomatology between the typical syndromes commonly described by these titles have not infrequently been reported. (Trower and Thursfield, 1921; Lewis, 1940; Dowling, 1940.) Dowling (1940) and Freudenthal (1940) have shown that the histological picture seen in the muscles in dermatomyositis is not essentially different from that in diffuse scleroderma. Calcinosis universalis may be more in the nature of a sequel to dermatomyositis or scleroderma than a variant of either syndrome, but may also occur independently of these conditions. Infection of unknown type and origin is generally considered to be the essential factor in the etiology of dermatomyositis, but penrsal of the literature provides little concrete proof of this. Karelitz and Welt (1932) discuss the various suggested causes, which include septicaemia, tuberculosis, toxaemia from food poisoning, and protozoal infestation: they consider that, in the two cases which they describe, the rise in temperature after massage during the acute stage, and after the removal of muscle for biopsy, supports the theory of infection: ' Unless an infection or toxin was stirred up, we are at a loss to explain this observation.' They also consider the microscopic appearance of the affected tissues suggestive of inflammation. Dowling (1940), on the other hand, thinks that the histological picture of the muscles is that of ' a degenerative myopathy, not a myositis.' Freudenthal (1940) states that most authors are disinclined to regard the lymphorrhages, which are constantly found in the affected tissues, as an inflammatory reaction; he draws attention to their resemblance to those found in the muscles in hyperthyroidism and myasthenia gravis. Griffiths (1940) also points out the resemblance between certain metabolic disturbances found in dermatomyositis (creatinuria and peripheral insulin resistance) and those seen in certain endocrine diseases, e.g. goitre, acromegaly, and pituitary basophilism. The prognosis in dermatomyositis is usually serious. Karelitz and Welt (1932), reviewing the literature, were able to collect eighteen cases of dermatomyositis in childhood, and they themselves added two more: of the twenty patients, eight died. Hecht (1940) described five cases, with two deaths. In the majority of fatal cases death is due to intercurrent pneumonia or sepsis. Of the victims who survive, the majority have a prolonged period of invalidism, varying from three months to several years, and a number are left with muscular atrophy and contractures. Treatment has been entirely symptomatic or empirical, and has generally appeared to have little influence on the course of the disease.