Clinically amyopathic dermatomyositis associated with anti-MDA5 antibody

Treatment of refractory anti-melanoma differentiation-associated gene 5 anbibody-positive dermatomyositis complicated by rapidly progressing interstitial pulmonary disease: Two case reports

BACKGROUND

Anti-melanoma differentiation-associated gene 5 antibody-positive (anti-MDA5 Ab⁺) dermatomyositis complicated with rapidly progressive interstitial lung disease (anti-MDA5 Ab⁺ DM-RP-ILD) has an unclear underlying mechanism with no recommended unified treatment plan. Herein, one of the cases that we report (Case 2) was successfully treated with tocilizumab despite having lung infection.

CASE SUMMARY

Case 1 was a 30-year-old woman who was admitted due to recurrent rash for 5 mo, fever and cough for 1 mo, and chest tightness for 3 d. She was diagnosed with non-myopathic dermatomyositis (anti-MDA5 Ab⁺) and interstitial pneumonia, and was treated with the combination of hormone therapy and cyclophosphamide followed by oral tacrolimus. Case 2 was a 31-year-old man admitted due to systemic rash accompanied by muscle weakness of limbs for more than 1 mo, and chest tightness and dry cough for 4 d. He was diagnosed with dermatomyositis (anti-MDA5 Ab⁺) and acute interstitial pneumonia with Pneumocystis jirovecii and Aspergillus fumigatus infections and was treated with hormone therapy (without cyclophosphamide) and the combination of tocilizumab and tacrolimus. The condition of both patients eventually improved and they were discharged and showed clinically stable condition at the latest follow-up.

CONCLUSION

Tocilizumab could be a salvage treatment for patients with anti-MDA5 Ab⁺ DM-RP-ILD who are refractory to intensive immunosuppression.

Treatment of refractory anti-melanoma differentiation-associated gene 5 anbibody-positive dermatomyositis complicated by rapidly progressing interstitial pulmonary disease: Two case reports

BACKGROUND

Anti-melanoma differentiation-associated gene 5 antibody-positive (anti-MDA5 Ab+) dermatomyositis complicated with rapidly progressive interstitial lung disease (anti-MDA5 Ab+ DM-RP-ILD) has an unclear underlying mechanism with no recommended unified treatment plan. Herein, one of the cases that we report (Case 2) was successfully treated with tocilizumab despite having lung infection.

CASE SUMMARY

Case 1 was a 30-year-old woman who was admitted due to recurrent rash for 5 mo, fever and cough for 1 mo, and chest tightness for 3 d. She was diagnosed with non-myopathic dermatomyositis (anti-MDA5 Ab+) and interstitial pneumonia, and was treated with the combination of hormone therapy and cyclophosphamide followed by oral tacrolimus. Case 2 was a 31-year-old man admitted due to systemic rash accompanied by muscle weakness of limbs for more than 1 mo, and chest tightness and dry cough for 4 d. He was diagnosed with dermatomyositis (anti-MDA5 Ab+) and acute interstitial pneumonia with Pneumocystis jirovecii and Aspergillus fumigatus infections and was treated with hormone therapy (without cyclophosphamide) and the combination of tocilizumab and tacrolimus. The condition of both patients eventually improved and they were discharged and showed clinically stable condition at the latest follow-up.

CONCLUSION

Tocilizumab could be a salvage treatment for patients with anti-MDA5 Ab+ DM-RP-ILD who are refractory to intensive immunosuppression.

[Treatment alternatives for amyopathic MDA5-positive dermatomyositis]

We report a case of an atypical course of therapy in amyopathic MDA5-antibody-positive dermatomyositis with interstitial lung disease. Due to the poor prognosis, early therapy with cyclophosphamide followed by rituximab was carried out initially in addition to the administration of prednisolone. Due to therapy failure, treatment was switched to mycophenolate mofetil. This showed a surprisingly rapid positive course in terms of interstitial lung disease, skin manifestation, and general disease activity.

Anti-MDA5 Amyopathic Dermatomyositis-A Diagnostic and Therapeutic Challenge

Clinically amyopathic Dermatomyositis (CADM) is a rare subtype of idiopathic inflammatory myositis, associated with no muscular manifestations, which is more frequent in Asian women. Anti-melanoma differentiation-associated gene 5 (MDA5) antibodies are a recently discovered type of specific autoantibodies associated with myositis. The anti-MDA5 DM was initially described in Japan and later it was discovered that the target antigen was a protein implicated in the innate immune response against viruses, that is encoded by the melanoma differentiation-associated gene 5. Anti-MDA5 DM is characteristically associated with distinguished mucocutaneus and systemic manifestations, including skin ulcerations, palmar papules, arthritis, and interstitial-lung disease. Patients with anti-MDA5 positivity have a high risk of developing rapid progressive interstitial-lung disease (RP-ILD), with a poor outcome. As a result, despite high mortality, diagnosis is often delayed, necessitating increased awareness of this possible condition. Despite a severe course of lung disease and an increased mortality rate, there is currently no standard treatment. Recent insights based on observational studies and case reports support combined therapy with immunosuppressive drugs and corticotherapy, as soon as the symptoms appear. The aim of this paper is to describe anti-MDA5 DM, focusing on the recent literature about the unique clinical manifestations and therapeutic options, starting from a severe clinical case diagnosed in our Rheumatology Department.

Anti-MDA5-associated dermatomyositis

Anti-MDA5-associated dermatomyositis (MDA5-associated DM) is an uncommon presentation of idiopathic inflammatory myositis, typically amyopathic, associated with rapidly progressive, treatment refractory interstitial lung disease and poor prognosis, particularly in patients with concomitant rapidly progressive interstitial lung disease (RP-ILD). We report two cases of MDA5-associated DM with fatal outcome in one of the patients, despite 'aggressive triple therapy' for RP-ILD.