FROM DYSPNEA TO DIAGNOSIS: ANTISYNTHETASE SYNDROME PRESENTING AS RAPIDLY PROGRESSIVE INTERSTITIAL LUNG DISEASE

Case Presentation: A 44‑year‑old woman with a history of gastroesophageal reflux disease (GERD) presented with progressive dyspnea, recurrent fevers, and arthralgias. Outpatient evaluation revealed restrictive pattern on pulmonary function tests, elevated inflammatory markers, ANA positivity, peripheral eosinophilia, and abnormal chest CT findings with lower lobe consolidations and traction bronchiectasis and concern for Interstitial lung disease (ILD). In the setting of worsening respiratory status, she underwent an outpatient bronchoscopy, which was unremarkable. It was initially suspected that the patient had ILD secondary to microaspirations from GERD. Within days, she was hospitalized for worsening hypoxia and near syncope, prompting surgical lung biopsy that demonstrated fibrotic ILD with organizing pneumonia and eosinophilic infiltrates. Serologies revealed strong anti‑PL12 and SSA 52 kDa antibodies, consistent with antisynthetase syndrome. Following initiation of corticosteroids, she experienced complete resolution of hypoxemic respiratory failure and was subsequently started on rituximab as an outpatient for continued treatment.

Discussion: Antisynthetase syndrome is a rare autoimmune disorder characterized by ILD, myositis, arthritis, fever, and hyperkeratotic skin changes (mechanic’s hands). Diagnosis is often delayed and requires a high level of coordination among multiple specialties by the hospitalist. This case illustrates the diagnostic complexity of ILD in the inpatient setting. Early diagnosis requires distinguishing autoimmune ILD from infectious and other etiologies that are not steroid‑responsive. ILD is a major source of morbidity and mortality in antisynthetase syndrome, and aggressive treatment significantly decreases mortality, particularly in rapidly progressive disease as seen in this case. Early recognition of the classic presentation of antisynthetase syndrome can facilitate earlier initiation of corticosteroids and increase the likelihood of achieving clinical remission.

Conclusions: Antisynthetase syndrome should be considered in patients with unexplained ILD, systemic autoimmune features, and recurrent hospitalizations for hypoxemia. Hospitalists are pivotal in recognizing typical and atypical presentations, coordinating specialty input, and ensuring timely initiation of immunosuppressive therapy to improve outcomes.