Hemophagocytic Lymphohistiocytosis Secondary to Chronic Lymphocytic Leukaemia and Multiple Infections Manifested with Quotidian Pyrexia: A Case Report

Hemophagocytic lymphohistiocytosis (HLH) is a rare, life-threatening immune regulatory condition that can cause end-organ damage and death. HLH is clinically characterized by uncontrolled activation of cytotoxic T lymphocytes, natural killer cells, and macrophages that can lead to a cytokine storm. Fever, hepatosplenomegaly, cytopenia, elevated liver enzymes, hypertriglyceridemia, hyperferritinemia, and hemophagocytosis in the bone marrow, spleen, or lymph nodes are the hallmarks of the disease. Its primary (genetic) form is typically observed in pediatric patients whereas its secondary, acquired form is seen in adult patients with an underlying autoimmune, malignant, or infectious disease. Here, we present a case of secondary hemophagocytic lymphohistiocytosis in a 70-year-old male with a history of chronic lymphocytic leukemia, severe prolonged COVID-19, and multiple infections who presented with persistent pyrexia of unknown origin (PUO). Diagnosis and management of HLH in adults are often extrapolated from the pediatric HLH-94 and HLH-2004 protocols. The management includes etoposide-based regimens containing corticosteroids, cyclosporine A, intravenous immunoglobulins (IVIG), intrathecal therapy, and liberal allogeneic stem cell transplant use in higher-risk patients. Due to the diverse clinical manifestations and the presence of numerous diagnostic mimics, the diagnosis of HLH is challenging. Since the prognosis is typically poor, prompt diagnosis and strong treatment are required. Here is a description of how our patient is diagnosed and treated based on the HLH 2004 protocol.