A Rare Case of Acute Fibrinous and Organizing Pneumonia Associated with Systemic Lupus Erythematosus and Autoimmune-associated Hemophagocytic Syndrome: The Involvement of CD163-positive Macrophages.

Acute fibrinous and organizing pneumonia (AFOP) is rare in patients with systemic lupus erythematosus (SLE). We herein report a case of AFOP with SLE and hemophagocytic syndrome. Early-phase high-resolution computed tomography showed a fine granular lung pattern. A pathological examination revealed AFOP. An immunohistological examination revealed numerous CD163+ and fewer CD68+ macrophages present in the lung tissue and in alveolar spaces as well, including fibrin balls, the interstitium, and bronchial walls. Pneumonia and thrombocytopenia worsened during high-dose steroid therapy, plasma exchange, and intravenous immunoglobulin administration. The addition of intravenous cyclophosphamide successfully ameliorated the symptoms and radiographic lesions. Therefore, this therapy may be useful for treating severe AFOP.