Paroxysmal Nocturnal Hemoglobinuria in Patients with Systemic Lupus Erythematosus: Diagnostic Challenges and Improvement with C5 Inhibitor Treatment.

The association between paroxysmal nocturnal hemoglobinuria (PNH) and systemic lupus erythematosus (SLE) remains unclear. A 34-year-old woman undergoing treatment for SLE developed progressive direct Coombs-negative hemolytic anemia due to PNH, as revealed by flow cytometric analysis. Anemia worsened, accompanied by elevated lactate dehydrogenase (LDH) levels and severe fatigue. Administration of the C5 inhibitor crovalimab resulted in improvement of anemia, reduction in LDH levels, and rapid clinical improvement, without major adverse effects. To the best of our knowledge, this is the first reported case of SLE complicated by PNH that was successfully and safely treated with crovalimab.