Acute Onset Seropositive Rheumatoid Arthritis-Associated Interstitial Lung Disease in the Absence of Articular Symptoms: An Atypical Presentation

Rheumatoid arthritis (RA) is a systemic autoimmune disease in which extra-articular manifestations, including interstitial lung disease (ILD), may precede joint involvement.Acute presentations mimicking pulmonary embolism (PE) or infection may delay diagnosis in similar cases.A 72-year-old previously healthy male presented with progressive dyspnea, cough, chest pain, and palpitations that began during a high-altitude hike in Hawaii.These symptoms persisted upon return home and worsened over almost two weeks.Initially believing he might have contracted pneumonia, the patient self-medicated with amoxicillin-clavulanate and azithromycin, which did not mitigate his symptoms.Ultimately, the severity of these symptoms prompted a call to emergency services.Upon arrival at the ED, he was noted to be hypoxic and tachypneic.CT angiography at the time demonstrated acute left-sided lobar pulmonary emboli and diffuse bilateral ground-glass opacities.Despite full anticoagulation and broadspectrum antibiotics, his respiratory failure progressed, requiring high-flow oxygen and intermittent bilevel positive airway pressure (BiPAP).Extensive infectious evaluation was negative.Autoimmune workup revealed elevated rheumatoid factor (30.7 IU/mL) and anti-cyclic citrullinated peptide antibodies (>250 U), with no clinical evidence of inflammatory arthritis.Imaging demonstrated diffuse interstitial and air-space disease with mediastinal lymphadenopathy and evolving complications including pneumothorax and subcutaneous emphysema.He was treated with pulse-dose methylprednisolone followed by mycophenolate without significant improvement and was ultimately transferred to a tertiary care center for further management.This case highlights an atypical, late-onset presentation of seropositive RA manifesting as severe ILD without preceding joint symptoms.The coexistence of acute PE and recent travel complicated early diagnostic reasoning.Clinicians should maintain suspicion for connective tissue disease-associated ILD in older patients with unexplained progressive hypoxemic respiratory failure and a negative infectious workup.