[A CASE OF CLINICALLY AMYOPATHIC DERMAMYOSITIS WITH INTERSTITIAL LUNG DISEASE SHOWING TWO DETERIORATIONS IN 4 YEARS].

We report the case of a 45-year-old man who was diagnosed with clinically amyopathic dermamyositis (CADM) and interstitial lung disease (ILD) after presenting with skin lesions typical of CADM and testing positive for anti-Melanoma Diferentiation-Associated gene 5 (anti-MDA5) anti-bodies. He was treated with a regimen including steroid pulse therapy, intravenous cyclophosphamide (IVCY), and calcineurin Inhibitor drug, which initially improved his ILD. However, three months post-treatment, the first deterioration of his conditions occurred, necessitating further administration of steroid pulse therapy and IVCY. After eight cycles of IVCY therapy, the serum levels of KL-6 and anti-MDA5 antibodies decreased, and reaching their lowest values. Nevertheless, two years and six months after the first observed deterioration, the second deterioration of his conditions occurred, leading to acute respiratory failure, treated again with steroid pulse therapy and IVCY. This treatment did not result in improvement of respiratory failure, therefore plasma exchange was attempted, which demonstrated a beneficial effect on the ILD for a short time. This case suggests that IVCY and plasma exchange might be effective therapeutic options for CADM with ILD.