Thrombotic thrombocytopenic purpura in a patient with systemic lupus erythematosus after anifrolumab: a possible association.

Anifrolumab, an inhibitor of the type I interferon receptor, is increasingly used for moderate to severe systemic lupus erythematosus (SLE). Although clinical trials report a favorable safety profile, real-world data remain limited. A 32-year-old woman with long-standing SLE developed fever, mucocutaneous bleeding, confusion, and seizures approximately ten weeks after initiating anifrolumab. Laboratory evaluation demonstrated microangiopathic hemolytic anemia, severe thrombocytopenia, elevated lactate dehydrogenase, and markedly reduced ADAMTS13 activity (10%). Other causes of thrombotic microangiopathy were excluded. The patient received plasma exchange, corticosteroids, caplacizumab, and rituximab, resulting in full neurologic and hematologic recovery. The close temporal relationship between anifrolumab initiation and onset of immune-mediated thrombotic thrombocytopenic purpura raises a possible drug-related association, although causality cannot be established from a single case. Clinicians should remain vigilant for new cytopenia or neurologic symptoms in patients starting interferon-pathway-targeted biologic therapy. Further pharmacovigilance is required to determine whether this represents a coincidental occurrence or a signal of potential risk.