Lung-only involvement in STING-associated vasculopathy with onset in infancy: a diagnostic pitfall in the absence of cutaneous vasculitis.

backgroundSTING-associated vasculopathy with onset in infancy (SAVI) is a rare monogenic autoinflammatory disorder. It is characterized by excessive interferon activity due to gain-of-function mutations in the STING1 gene, resulting in skin lesions and lung involvement. Some patients may also present with interstitial lung disease (ILD) only. While treatment with JAK inhibitors like baricitinib has shown some promise, long-term success is limited. CASE PRESENTATION: We report on a 10-month-old male suffering from respiratory distress since birth. He demonstrated failure to thrive and progressive ILD. The patient lacked skin lesions, arthritis, hepatosplenomegaly, lymphadenopathy, and any clues indicating vasculitis. Erythroid sedimentation rate was normal, and C‑reactive protein (CRP) was slightly elevated. However, CRP became elevated to 115 mg/L during the course of disease. Despite antibiotics and steroids, his condition deteriorated. Chest imaging revealed features suggestive of ILD, prompting further investigation. Whole-exome sequencing confirmed a heterozygotic c.461A > G (p.Asn154Ser) variant in the STING1 gene, thereby diagnosing the patient with SAVI. Despite treatment with baricitinib and tocilizumab, his condition worsened, and he ultimately passed away.

conclusionThis case highlights that SAVI should be considered in the differential diagnosis of ILD, even without typical skin lesions.