Anti-MDA5 antibody positive dermatomyositis complicated by interstitial lung disease with an improved outcome: A case report.

RATIONALE: Anti-melanoma differentiation-associated gene 5 (MDA5) antibody positive dermatomyositis (MDA5-DM) is an autoimmune disease, characterized by a particular skin ulcer and rapidly progressive interstitial lung disease (RP-ILD). This case highlights diagnostic challenges of this disease and underscores the importance of early recognition and timely intervention.

PATIENT CONCERNS: A 59-year-old woman presented to the hospital with systemic myalgia, fatigue, and anorexia. Following admission she developed recurrent fever. Computed tomography of the chest and bronchoalveolar lavage fluid analysis revealed severe pulmonary infections. Despite 2 weeks of antimicrobial therapy yielding radiographic improvement, her dermatomyositis symptoms worsened.

DIAGNOSES: Immune profiling and myositis-specific antibody testing confirmed the diagnosis of MDA5-DM-ILD.

INTERVENTIONS: The following treatment included methylprednisolone combined with immunosuppressants (tofacitinib, tacrolimus, tocilizumab, mycophenolate mofetil). Subsequent computed tomography imaging demonstrated cavity lesions and micronodules, with lung biopsy confirming fungal and viral coinfections. Therapy was adjusted to sustained methylprednisolone (22 mg/d), tacrolimus (0.5 g/d), targeted antimicrobials (ganciclovir, voriconazole) and prophylactic use of sulfamethoxazole complex.

OUTCOMES: At discharge, the patient achieved clinical stability with resolved fever, normalized oxygen saturation and improved myalgia, though mild epigastric discomfort persisted.

LESSONS: MDA5-DM-ILD poses challenges for clinicians due to its diagnostic difficulty, rapid progression and secondary infection risks. Early immunosuppression combined with infection prevention is the key to a successful treatment of this disease.