Covid-19, a new possible mimicker of interstitial lung disease related to primary Sjögren’s syndrome: a case report.

Introduction: Acute exacerbation of interstitial lung disease (ILD) and COVID-19 pneumonia show many similarities, but also COVID-19 sequelae, mainly when fibrotic features are present, can be difficult to distinguish from chronic ILD observed in connective tissue diseases (CTD). Case report: In 2018, a 52-year-old woman, was diagnosed with pSS. The patient complained of no respiratory symptoms and a chest x-Ray was normal. During March 2020, the patient was hospitalized for acute respiratory failure related to COVID-19 pneumonia. Three months later, follow-up chest HRCT showed ground glass opacity (GGO) and interlobular interstitial thickening. Pulmonary function tests (PFT) showed slight restrictive deficit and mild reduction in diffusion lung of carbon monoxide (DLCO). The patient complained of asthenia and exertional dyspnoea. A multidisciplinary discussion including rheumatologist, pulmonologist, and thoracic radiologist didn’t allow a definitive differential diagnosis between COVID-19 persisting abnormalities and a previous or new-onset pSS-ILD. A wait and see approach was decided, monitoring clinical conditions, PFTs and chest HRCT over time. Only 2 years after the hospitalization, a slight improvement of clinical symptoms was reported; PFT also improved; a follow-up HRCT showed almost complete resolution of GGO and interlobular interstitial thickening, confirming the diagnostic hypothesis of long-COVID lung manifestations. Discussion: In the above-reported case report, 3 differential diagnoses were possible: a COVID-19 related ILD, a pre-existing pSS-ILD or a new-onset pSS-ILD triggered by COVID-19. Regardless of the diagnosis, the persistence of clinical and PFT alterations, suggested a chronic disease but, surprisingly, clinical and radiologic manifestations rapidly disappeared after about 2 years.