Unusual presentation of anti- synthetase syndrome as usual interstitial pneumonia pattern: A case report with systematic review of literature

Anti-synthetase syndrome (ASS) is an uncommon autoimmune connective tissue disorder with a heterogeneous clinical spectrum, in which interstitial lung disease (ILD) may occur as an isolated or predominant manifestation. Non-specific interstitial pneumonia is the most frequently reported radiological pattern, whereas usual interstitial pneumonia (UIP) is relatively uncommon. We report a 23-year-old male who presented with gradually progressive dyspnea and dry cough of 5 years’ duration and had previously received empirical anti-tubercular therapy despite repeatedly negative microbiological investigations. High-resolution computed tomography of the thorax demonstrated a definite UIP pattern, initially raising the possibility of idiopathic pulmonary fibrosis. However, given the patient’s young age and atypical clinical presentation, we evaluated for connective tissue disease. Myositis-specific antibody testing demonstrated strong positivity for anti-PL-12 antibodies, establishing the diagnosis of anti-synthetase syndrome despite the absence of clinical features of myositis, arthritis, Raynaud phenomenon, or mechanic’s hands. The patient was treated with systemic corticosteroids, nintedanib, and subsequently rituximab, with significant clinical and functional improvement. This case highlights that ASS may rarely present with an isolated UIP pattern and without overt extrapulmonary manifestations. In young patients presenting with UIP, particularly when the clinical profile is atypical for idiopathic pulmonary fibrosis, comprehensive autoimmune evaluation should be considered.