Management of anti-melanoma differentiation-associated gene 5 antibody-induced refractory dermatomyositis complicated by interstitial pneumonia using tofacitinib and its outcomes: a case report.

Background: Clinical amyopathic dermatomyositis is characterized by cutaneous symptoms but lacks muscle symptoms. Anti-melanoma differentiation-associated gene 5 antibodies are frequently found in Japanese patients with clinical amyopathic dermatomyositis. Patients with rapidly progressive interstitial lung disease with positive anti-melanoma differentiation-associated gene 5 antibodies have poor prognoses, and majority of them are treated with combination immunosuppressive therapy; however, the best treatment is yet to be determined.

Case presentation: A 52-year-old Asian male patient presented with a chief complaint of dyspnea on exertion. He had a typical skin rash and rapidly progressive interstitial pneumonia. Additionally, anti-melanoma differentiation-associated gene 5 antibodies were detected; therefore, he was diagnosed with dermatomyositis-associated interstitial pneumonia. Respiratory failure worsened despite administering steroid pulse therapy, tacrolimus, and cyclophosphamide. Consequently, plasma exchange was performed on day 13 of admission. After a slight improvement, the patient's respiratory failure worsened. Thus, cyclophosphamide was replaced by tofacitinib on day 28. Although respiratory failure improved and the progression of interstitial pneumonia seemed under control, βD-glucan level increased and Aspergillus antigen was detected on day 49. Micafungin and voriconazole were administered, but the patient succumbed to worsening respiratory failure on day 61. The pathological autopsy revealed multiple nodular lesions with cavity formation in both lungs and the presence of Aspergillus with severe neutrophilic infiltration and necrosis, which supported the diagnosis of invasive pulmonary aspergillosis.

Conclusion: The patient with anti-melanoma differentiation-associated gene 5 antibody-related rapidly progressive interstitial lung disease, whose disease was difficult to control after the administration of triple immunosuppressive therapy (steroids, tacrolimus, and cyclophosphamide), showed good response with tofacitinib. Unfortunately, the patient died of invasive pulmonary aspergillosis owing to severe immunosuppression; thus, the signs of complications should be promptly detected.