Profound hematologic instability in consanguinity-associated familial hemophagocytic lymphohistiocytosis: a pediatric case report.

Introduction and Background: Familial hemophagocytic lymphohistiocytosis (FHL) is a rare, life-threatening systemic inflammatory disorder characterized by excessive immune activation. It is primarily caused by mutations affecting cytotoxic function in natural killer cells and cytotoxic T lymphocytes. Early diagnosis and treatment are crucial due to the condition's rapid progression and high mortality without intervention. Case Presentation: In August 2023, a 3-year-old Asian male patient was admitted, exhibiting symptoms of high fever, jaundice, and hepatosplenomegaly. Initial investigations revealed pancytopenia, elevated ferritin, and bone marrow hemophagocytosis, leading to a diagnosis of FHL. Patient was referred to the oncology department and started on initial chemotherapy with vinblastine, prednisolone, and mercaptopurine and continuation chemotherapy therapy with vinblastine. In May 2024, the patient re-presented with febrile episodes, a productive cough, and pleural effusion, findings indicative of pneumonia. Laboratory findings revealed persistent hematological instability characterized by thrombocytopenia and leukopenia, with episodes of leukocytosis, alongside deranged liver function tests. Management included antibiotics and supportive care, highlighting recurrent hematologic instability and pleural involvement in FHL management. Clinical Discussion: In our patient's case, cytopenias played a critical role, underscoring profound hematologic instability and immune system dysfunction characteristic of FHL. Hyperferritinemia, indicative of intense inflammation and immune activation, was notable. The involvement of pleura further emphasizes the systemic nature of FHL, necessitating aggressive treatment with antibiotics and antifungal agents. Current management strategies encompass chemotherapy, antibiotics, and comprehensive supportive care. Prognosis varies, highlighting the importance of early diagnosis and adherence to treatment. Conclusion: This case underscores the diagnostic challenges and therapeutic complexities in managing FHL, particularly in the context of consanguinity and genetic predisposition. Advances in genetic testing and treatment modalities are critical for improving outcomes and long-term prognosis in FHL. Continued research is essential to refine diagnostic criteria and therapeutic strategies for optimal patient care.