Macrophage Activation Syndrome in a Patient With a Recent Diagnosis of Systemic Lupus Erythematosus – A Report of Successful Treatment With Dexamethasone and Human Immunoglobulin

Abstract

BACKGROUNDMacrophage activation syndrome (MAS) is a severe and potentially fatal hyperinflammatory condition characterized by excessive macrophage and T cell activation resulting in multiple organ dysfunction. MAS is considered a secondary or acquired form of hemophagocytic lymphohistiocytosis (HLH) and is usually associated with infection, malignancy, or in the context of rheumatologic disorders, such as systemic lupus erythematosus (SLE). In SLE, MAS can mimic underlying disease activity because both entities share some common features, such as fever, lymphadenopathy, splenomegaly, and blood cytopenias. This overlap in clinical presentations can make it difficult to recognize MAS and delay the definition of the most appropriate therapeutic approach. CASE REPORTA 16-year-old female patient, started in February 2022 with fatigue, edema in the lower limbs with ascending progression, evolving to anasarca, hypertension and oliguria, referred for hospitalization. On admission exams she had anemia, lymphopenia, fine speckled nuclear ANA pattern (1/160), consumption of complements and positive autoantibodies (anti-RO, anti-RNP and anti-SM), protein/creatinine ratio at nephrotic level. Pulse therapy with methylprednisolone and cyclophosphamide was started, and renal biopsy showed class III lupus nephritis. Patient evolved with persistent fever, without improvement after antibiotic therapy, splenomegaly, pancytopenia with worsening of the general condition, need for transfer to intensive care unit, intubation and initiation of renal replacement therapy. Laboratory review showed elevated ferritin, lactic dehydrogenase, fibrinogen, prolonged activated partial thromboplastin time and hypertriglyceridemia. A myelogram was performed, which confirmed the main diagnostic hypothesis, MAS, due to the presence of hemophagocytosis. Treatment with dexamethasone 10 mg/m² of body surface and intravenous human immunoglobulin 1 g/kg was started. One week after the start of treatment, the patient showed clinical and laboratory improvement, and monthly cyclophosphamide was maintained and dexamethasone was gradually reduced. CONCLUSIONMacrophage activation syndrome should be included in the differential diagnosis of SLE patients with persistent fever and pancytopenia. The mortality rate of MAS is high and therefore prompt initiation of treatment is of utmost importance.