Mycophenolate mofetil after tacrolimus for refractory clinically amyopathic dermatomyositis: a case report

Abstract

Dermatomyositis (DM) positive for anti-melanoma differentiation-associated gene 5 (MDA5) antibodies, mainly when linked with rapidly progressive interstitial lung disease (RP-ILD), is considered a refractory disease. Our report describes a critical case of clinically amyopathic dermatomyositis (CADM) with RP-ILD that tested positive for both anti-MDA5 and anti-Ro-52 antibodies. The patient showed a limited response to a combined therapy regimen of prednisone, iguratimod, and tacrolimus. However, after adjunct therapy with mycophenolate mofetil (MMF), the patient's condition was controlled, his serum KL-6 levels decreased, and anti-MDA5 antibodies became negative. During the 68-week follow-up, the patient's condition remained stable, with a satisfactory quality of life. This report also discusses the potential role of inflammatory cytokines in the pathophysiology of CADM and RP-ILD. Further research is required to confirm these results and investigate the application of MMF in maintenance therapy for CADM-associated RP-ILD.

Keywords: anti-MDA5-associated dermatomyositis; case report; clinically amyopathic dermatomyositis (CADM); mycophenolate mofetil; rapidly progressive interstitial lung disease.

FIGURE 1

Gottron’s papules on the extensor surfaces of the elbows. Erythematous, scaly, and slightly raised papules are present bilaterally over the elbows, consistent with Gottron’s papules, a characteristic cutaneous manifestation of dermatomyositis.

FIGURE 2

Chest HRCT of the patient with interstitial lung disease associated with MDA5-DM. (A, B) Baseline CT scans reveal extensive bilateral ground-glass opacities and consolidation in the lungs, indicating active disease. (C, D) Follow-up scans at 4 weeks indicate a slight reduction in ground-glass opacities but persistent consolidation, indicating partial improvement. (E, F) By 12 weeks, HRCT shows significant disease progression characterized by widespread bilateral consolidations, persistent ground-glass opacities, and newly developed reticular opacities, suggestive of advancing interstitial fibrosis. (G, H) At 44 weeks, significant resolution of ground-glass opacities and consolidation, with further fibrotic changes indicating chronic scarring. (I, J) By 68 weeks, there is continued improvement with minimal residual ground-glass opacities and consolidation. Fibrotic changes remain stable, indicating a near-complete response to treatment and stabilization of chronic changes.

FIGURE 3

Treatment Process and Cytokine Changes. (A) Prior to treatment; (B) 4 weeks after treatment with a methylprednisolone pulse followed by oral methylprednisolone (40 mg qd), oral tacrolimus (1 mg bid), and nintedanib at 100 mg bid; (C) 12 weeks after treatment with a prednisone pulse and tacrolimus and then conversion from tacrolimus to MMF 1500 mg qd, continuing to oral prednisone 50 mg qd, iguratimod 25 mg bid, and nintedanib 100 mg bid; (D) 20 weeks after treatment, oral prednisone 40 mg qd, MMF 1000 mg qd, iguratimod 25 mg bid, and nintedanib 100 mg bid; (E) 44 weeks after treatment, oral prednisone 15 mg qd, MMF 1000 mg qd, iguratimod 25 mg bid, and nintedanib 100 mg bid; (F) 68 weeks after treatment, oral prednisone 5 mg/d, MMF 750 mg qd, and iguratimod 25 mg qd. MMF, mycophenolate mofetil. The line chart shows IL-8, FER, IL-10, and IL-17A levels over the 68-week treatment period.