Ai Nishida

Rationale: Respiratory syncytial virus (RSV) is a common cause of lower respiratory tract infections in older adults. In systemic sclerosis, interstitial lung disease is a frequent, serious complication requiring immunosuppressive therapy. Differentiating RSV pneumonia from systemic sclerosis-associated interstitial lung disease (SSc-ILD) is essential for appropriate management and to avoid initiating immunosuppressive agents that may be harmful in cases of RSV pneumonia. Patient concerns: An 85-year-old woman with limited cutaneous systemic sclerosis and dementia presented with a 1-week history of nonproductive cough and fever. Diagnoses: Chest computed tomography (CT) showed bilateral consolidations, bronchial wall thickening, and mucus plugs, suggesting airway infection. However, both respiratory symptoms and CT findings worsened, and sputum and blood cultures remained negative. To differentiate SSc-ILD from viral infection, multiplex PCR testing (FilmArray) of a pharyngeal swab was performed, detecting RSV and confirming RSV pneumonia. Interventions: The patient was initially treated with intravenous ceftriaxone, then given prednisolone at 0.6 mg/kg/d after RSV was diagnosed. Outcomes: Her respiratory symptoms and CT findings improved, and she was discharged on day 16 with tapering corticosteroids. Lessons: Multiplex PCR is useful for detecting RSV pneumonia in patients with autoimmune diseases. Clinicians should be aware that RSV infection can occur in these patients and should consider RSV pneumonia as an important differential diagnosis of SSc-ILD.