Anifrolumab as a therapeutic option in mixed connective tissue disease with autoimmune cytopenia: a case report and narrative review of the literature.

Mixed connective tissue disease (MCTD) represents a complex autoimmune condition characterized by vasculopathy, fibrosis, and immune dysregulation. Autoimmune cytopenias are rare but clinically significant complications that increase morbidity and complicate management of these diseases. Current therapies, including glucocorticoids and conventional immunosuppressants, may be limited by intolerance or inadequate hematologic response. Type I interferon (IFN) signaling has emerged as a key pathogenic pathway, and its blockade represents a novel therapeutic approach. We describe a 39-year-old woman with MCTD and clinical features of systemic sclerosis, presenting with Raynaud's phenomenon, digital ischemic ulcers, esophageal involvement, and pulmonary arterial hypertension. Her disease course was complicated by progressive cytopenia, including leukopenia, severe lymphopenia, mild anemia, and thrombocytopenia. Azathioprine therapy led to worsening pancytopenia, necessitating discontinuation, while glucocorticoids provided only partial hematologic recovery. Subsequent treatment with mycophenolate was ineffective. Introduction of anifrolumab (300 mg IV every 4 weeks) resulted in hematologic improvement, with normalization of hemoglobin and stabilization of leukocyte and platelet counts, without infusion-related adverse events. The findings support type I IFN blockade as a promising therapeutic avenue in refractory hematologic manifestations of connective tissue disease, warranting further investigation in larger studies.