Abstract
RATIONALE: Melanoma differentiation-associated gene 5 (MDA5)-associated rapidly progressive interstitial lung disease (RPILD) is a rare and life-threatening condition with no standardized treatment protocol. We report a case of successful treatment using a novel combination therapy. PATIENT CONCERNS: A 69-year-old female presented with progressive dyspnea and chest tightness that had persisted for 1 year but significantly worsened over the 20 days before admission. The recent exacerbation was accompanied by coughing, expectoration, and fatigue. DIAGNOSES: Following a comprehensive evaluation including chest computed tomography imaging, laboratory tests, and autoantibody profiling, the patient was diagnosed with MDA5-associated RPILD. INTERVENTIONS: The patient was treated with high-dose methylprednisolone pulse therapy, cyclophosphamide, and telitacicept (a novel TACI-Fc fusion protein). OUTCOMES: After treatment, the patient's oxygenation index improved from 174 to 306 mm Hg. Follow-up chest computed tomography showed near-complete resolution of bilateral lung inflammation. Pulmonary function tests demonstrated improvement, with diffusing capacity for carbon monoxide reaching 63.6% of the predicted value at 6-month follow-up. LESSONS: This case suggests that combination therapy including telitacicept may be effective for MDA5-associated RPILD. Further research is needed to confirm these findings and elucidate the underlying mechanisms of action.