Dermatomyositis

Excerpt

Dermatomyositis is a rare acquired immune-mediated muscle disease characterized by muscle weakness and skin rash. It is classified as one of the idiopathic inflammatory myopathies (IIM). Although all idiopathic inflammatory myopathies share the common presentation of muscle weakness, they differ clinically in terms of muscle groups involved and histopathological findings. Dermatomyositis presents with characteristic skin findings and symmetric proximal skeletal muscle weakness. Also, it can affect other organ systems such as the pulmonary, cardiovascular, and gastrointestinal systems. A significant proportion of patients with dermatomyositis have an underlying malignancy, which can alter the prognosis of the condition. Although a majority of cases have muscular and cutaneous manifestations, other variants of the condition exist. Clinically amyopathic dermatomyositis (CADM) is a condition in which patients have the characteristic cutaneous findings of dermatomyositis, but do not have muscle weakness. Clinically amyopathic dermatomyositis is further classified as hypomyopathic or amyopathic dermatomyositis. Patients with hypomyopathic dermatomyositis lack muscle weakness clinically. However, there is evidence of myositis based on laboratory investigations, electromyography, or muscle biopsy. In contrast, patients with amyopathic dermatomyositis lack both clinical and laboratory evidence of muscle involvement.