Amyopathic dermatomyositis (Q55809)

Amyopathic dermatomyositis is a variant of dermatomyositis that is characterised by the typical skin rash but without the muscle abnormalities. The amyopathic state is defined by a lack of muscle weakness and through diagnostic tests, including serum muscle enzymes, electromyogram studies, and muscle biopsies, that are usually normal or show only minimal abnormalities. Despite the lack of weakness, many patients complain of debilitating fatigue. The amyopathic form is more commonly seen in adults than in children, although juvenile cases are reported. Some early series suggested no association with underlying malignancies, but recent reports indicate that malignancies occur.