Anti-NOR90 antibodies and their clinical significance: a multicenter experience in southern Spain.

Introduction: Anti-NOR90 antibodies were initially described in patients with autoimmune diseases based on staining of a nucleolar region known as the nucleolar organizer region (NOR). This study aims to explore the clinical aspects of anti-NOR90 antibodies in patients with systemic autoimmune diseases.

Methods: Observational study of patients with positive anti-NOR90 antibodies using the EUROLINE Systemic Sclerosis profile (IgG) kit (Euroimmun, Germany). Data on demographics, comorbidities, autoimmune diseases, treatment, and clinical manifestations were collected.

Results: Fifteen Patients with positive anti-NOR90 antibodies were included. Majority were female (86.7%), with median age of 54 years. Most common clinical manifestations were Raynaud's phenomenon, dryness, and interstitial lung disease (ILD). Some patients had hematological or solid organ neoplasms. EPID was prevalent, with one case showing rapid progression requiring aggressive treatment.

Discussion and conclusion: This study highlights the association between anti-NOR90 antibodies and systemic autoimmune diseases, particularly SS and ES. EPID was a notable feature, suggesting its consideration in IPAF diagnosis for anti-NOR90 positive patients. Further multicenter studies are needed for better understanding and detection methods optimization.