Lactic acidosis in hemophagocytic syndrome: diagnostic and therapeutic challenges in the intensive care unit-a case series.

Background: Hemophagocytic lymphohistiocytosis is a life-threatening hyperinflammatory syndrome resulting from uncontrolled activation of T cells and macrophages, frequently leading to multiorgan failure. Severe lactic acidosis (lactate ≥ 10 mmol/L), a rare yet critical manifestation, poses unique diagnostic and therapeutic challenges in the intensive care unit. Here, we report two cases of Chinese men with hemophagocytic lymphohistiocytosis presenting with extreme lactic acidosis, highlighting the necessity of early hemophagocytic lymphohistiocytosis screening in intensive care unit patients with unexplained hyperlactatemia.

Case presentation: Case 1: A 43-year-old Chinese male with diffuse large B cell lymphoma developed hemophagocytic lymphohistiocytosis, presenting with lactate 14.2 mmol/L, cytopenia, and hyperferritinemia. Etoposide therapy rapidly normalized lactate levels (within 24 hours) and led to complete recovery after autologous stem cell transplantation. Case 2: A 60-year-old Chinese male with chronic gout and soft tissue infection developed septic shock and reactive hemophagocytic lymphohistiocytosis (lactate 14.3 mmol/L). Despite initial response to etoposide, he succumbed to invasive aspergillosis due to treatment-related immunosuppression.

Conclusion: Extreme lactic acidosis in intensive care unit patients should prompt urgent hemophagocytic lymphohistiocytosis evaluation, particularly in Chinese populations. Etoposide is effective for malignancy-associated hemophagocytic lymphohistiocytosis, while reactive hemophagocytic lymphohistiocytosis may require tailored immunosuppression with strict infection prophylaxis. Routine reporting of patient ethnicity aids epidemiological understanding of rare diseases such as hemophagocytic lymphohistiocytosis.