Coexistence of anti-KS and anti-TIF1-γ antibodies in clinically amyopathic dermatomyositis presenting with rapid progression of interstitial lung disease.

Polymyositis/dermatomyositis (DM) is an idiopathic inflammatory myopathy manifesting mainly as symmetrical proximal muscle weakness and/or typical cutaneous features due to autoimmune mechanisms. Clinically amyopathic dermatomyositis (CADM) is a subset of DM that exhibits only the typical cutaneous features without any clinical muscle symptoms. Several autoantibodies have been found specifically in patients with polymyositis/DM, including CADM patients. The anti-KS antibody is one of a group of anti-aminoacyl transfer RNA antibodies that are mainly associated with fever, Raynaud's phenomenon, polyarthritis, and interstitial lung disease (ILD), whereas anti-TIF1-γ antibody is frequently found in DM patients with malignancy. Here, we report a CADM patient having both anti-KS antibody and anti-TIF1-γ antibody. This patient developed an acute exacerbation of ILD and was successfully treated with high-dose corticosteroid pulse therapy together with immunosuppressive agents. Although earlier experience had indicated that the seminal characteristic of anti-KS-positive ILD was slowly developing disease onset with little or no progression over the clinical course, the present patient suffered rapidly progressive disease.