Clinically amyopathic dermatomyositis (CADM) is a subset of dermatomyositis, where there is skin involvement without myositis. There is no or little muscle weakness and serum CPK levels are normal or mildly elevated. Patients with one of the variants of CADM present with ulcerated Gottron’s papules and rapidly progressive interstitial lung disease (RP-ILD). Anti-MDA5 (anti-melanoma differentiation-associated antibody is positive in about 60-70% of CADM patients.
The disease is rapidly progressive and is associated with high mortality. Aggressive immunotherapy with high-dose corticosteroids, cyclosporine and intermittent intravenous cyclophosphamide is recommended for anti-MDA5 antibody-positive CADM.