Subacute cutaneous lupus erythematosus, and positive anti-MDA5 antibody in clinically amyopathic dermatomyositis with rapidly progressive interstitial lung disease: A case report and literature review

Background: Clinically amyopathic dermatomyositis (CADM) is a subtype of DM with characteristic cutaneous lesion with normal creatinine kinase levels. Presence of anti-melanoma differentiation-associated gene 5 (MDA5) antibody is found to be associated with rapidly progressive interstitial lung disease (RP-ILD). Aim of the work: to report a CADM patient with positive anti-MDA5 antibody and RP-ILD with clinical features of systemic lupus erythematosus (SLE) who clinically responded to a combination of cyclophosphamide and other conventional immunosuppressant. Case presentation: A 44-year-old Indian woman presented with classical cutaneous lesions of DM with normal creatinine kinase levels amongst other clinical features. She was initially diagnosed with SLE before developing RP-ILD and a positive MDA5 antibody. Anti-nuclear antibody, anti-dsDNA and anti-Sm antibody were negative. Serum ferritin level was very high (1599 ng/mL) as compared to C-reactive protein (23.4 mg/L). Anti-Ro-52 and anti-PM-Scl 75 were positive. High resolution computed tomography (HRCT) of the lungs revealed features consistent with ILD. Histology of her skin biopsy was consistent with subacute cutaneous lupus erythematosus (SCLE). Her diagnosis was revised to CADM with overlapping SCLE. She responded to a combination of hydroxychloroquine, cyclosporine-A, mycophenolate mofetil, pulse methylprednisolone and pulse cyclophosphamide 750 mg/month for 6 months. Her cutaneous lesions gradually improved with normalization of serum ferritin level. Repeated HRCT showed no further progression of the pulmonary fibrosis. Conclusion: CADM with positive anti-MDA5 antibody associated with RP-ILD is rare with a high mortality rate. Early recognition and prompt treatment with a combination of immunosuppressant may improve the outcome of this complex disease. (C) 2021 Egyptian Society of Rheumatic Diseases. Publishing services provided by Elsevier B.V.