Occult primary Sjögren Syndrome in patients with interstitial pneumonia with autoimmune features

To define the performance of Minor Salivary Gland Biopsy (MSGB) and Dry Eye Tests (DET) to detect occult Sjögren Syndrome (SS) among Interstitial Pneumonia with Autoimmune Features (IPAF) patients.

Prospective study. Interstitial Lung Disease (ILD) patients without defined Connective Tissue Disease and one or more IPAF classification domains or xerophthalmia were included. MSGB, Schirmer's test (ST) and Ocular Staining Score (OSS) were performed in a blinded manner by experienced specialists. MSGB with ≥1 focus of lymphocytes and Dry Eye Test (DET) with OSS ≥ 5 and/or ST < 5 s were considered positive. SS was diagnosed according to the ACR 2016 criteria.

534 patients on the first consult were screened. 67 patients had at least one IPAF criteria, 53 (79.1%) female, mean age (SD) 64.2 years old (10.8). Positive ST in 36 (53.7%), positive OSS in 29 (43.3%) and positive MSGB in 36 (53.7%) were found. Finally, 27 (40.3%) met SS diagnostic criteria. 25 (37.3%) and 18 (26.8%) of them did not report dry eyes or dry mouth, respectively. 53 (79.1%) had negative anti SSA/Ro, 57 (85.1%) had negative anti LA/SSB, 30 (44.7%) had negative ANA, and 52 (77.6%) had negative RF, respectively. A significantly higher proportion of ANA (+), anti-SSA/Ro (+), anti-SSB/La (+), positive DET and positive MSGB were found in the SS population.

A significant proportion of patients with occult SS were found in our study. MSGB and DET may be considered in the evaluation of IPAF patients.