Inaugural complete heart block in anti-SSA negative systemic lupus erythematosus: the diagnostic role of anti-PM-Scl 100 antibodies

This study presents a rare case of complete heart block (CHB) in a 21-year-old woman with systemic lupus erythematosus (SLE) who tested negative for anti-SSA/Ro antibodies, which are typically associated with CHB. Instead, the presence of anti-PM-Scl 100 antibodies and microvascular changes observed through nailfold capillaroscopy were significant. These findings suggest that CHB in SLE may result from a microvascular-driven process rather than acute inflammation. The case emphasizes the importance of considering extended antibody profiling and microvascular assessment in diagnosing unexplained heart block in young adults, as traditional reliance on Ro/La antibodies may overlook atypical autoimmune presentations.