A Case of Hemophagocytic Lymphohistiocytosis (HLH) Secondary to T Cell Lymphoma and Cytomegalovirus (CMV) Infection and Complicated by Tumor Lysis Syndrome (TLS)

A Case of Secondary Hemophagocytic Lymphohistiocytosis in a Patient With T-cell Lymphoma

Hemophagocytic lymphohistiocytosis (HLH) is a rare and life-threatening condition that results from excessive immune activation and inflammation. This condition may be triggered by various factors, including infections, malignancies, or autoimmune diseases. Here, we report the case of a 39-year-old male who developed HLH secondary to T-cell lymphoma and had a history of multiple autoimmune disorders. Our patient presented with shortness of breath and weakness which led to an admission for methicillin-resistant Staphylococcus aureus bacteremia. His hospital course deteriorated rapidly due to his worsening condition. He was confirmed to have HLH based on the HLH-2004 criteria with the presence of fever, splenomegaly, hypertriglyceridemia, hypofibrinogenemia, low natural killer cell function, high ferritin, and soluble interleukin 2 receptor levels. Peripheral blood smear and bone marrow biopsy showed atypical lymphocytes consistent with a T-cell lymphoma, but no hemophagocytosis. He was treated with dexamethasone and etoposide. Despite treatment, the patient passed away. This case aims to contribute further to the understanding of secondary HLH in the setting of T-cell lymphoma. It also illuminates how vital early recognition and treatment are in patients with secondary HLH.

An Unusual Case of Phagocytic Histiocytes on Peripheral Blood Smear of a Patient With Methicillin-Resistant Staphylococcus aureus (MRSA) Endocarditis

Hemophagocytic lymphohistiocytosis (HLH) is a rare disorder of the immune system that may rapidly progress into life-threatening complications. There is uncontrolled activation of histiocytes and phagocytic macrophages, resulting in excess secretions of cytokines that manifest into systemic hyperinflammation affecting several organs. HLH may present as primary due to underlying familial or genetic causes or as secondary due to underlying conditions such as malignancies, infections, or autoimmune disorders. This case is of a seven-year-old girl who developed culture-proven MRSA infective endocarditis. She received sensitivity-tailored antimicrobial treatment. Initially unremarkable, but later her peripheral blood smear showed the presence of large histiocyte-like cells showing hemophagocytic activity of moderate grade (two to five histiocytes with hemophagocytosis/slide) on the feathered edge of the slide. Peripheral film findings triggered further workup for HLH. Her condition later deteriorated, requiring high-dependency unit care. This case highlights the significance of maintaining a high index of suspicion with subsequent laboratory work in cases that develop cardinal diagnostic criteria for clinical manifestations of HLH. It also emphasizes reviewing the feathered edges of blood smears to prevent overlooking important morphological findings.

Etoposide: A rider on the cytokine storm

For more than 40 years, the epipodophyllotoxin drug etoposide is prescribed to treat cancer. This semi-synthetic compound remains extensively used to treat advanced small-cell lung cancer and in various chemotherapy regimen for autologous stem cell transplantation, and other anticancer protocols. Etoposide is a potent topoisomerase II poison, causing double-stranded DNA breaks which lead to cell death if they are not repaired. It is also a genotoxic compound, responsible for severe side effects and secondary leukemia occasionally. Beyond its well-recognized function as an inducer of cancer cell death (a "killer on the road"), etoposide is also useful to treat immune-mediated inflammatory diseases associated with a cytokine storm syndrome. The drug is essential to the treatment of hemophagocytic lymphohistiocytosis (HLH) and the macrophage activation syndrome (MAS), in combination with a corticosteroid and other drugs. The use of etoposide to treat HLH, either familial or secondary to a viral or parasitic infection, or treatment-induced HLH and MAS is reviewed here. Etoposide dampens inflammation in HLH patients via an inhibition of the production of pro-inflammatory mediators, such as IL-6, IL-10, IL-18, IFN-γ and TNF-α, and reduction of the secretion of the alarmin HMGB1. The modulation of cytokines production by etoposide contributes to deactivate T cells and to dampen the immune stimulation associated to the cytokine storm. This review discussed the clinical benefits and mechanism of action of etoposide (a "rider on the storm") in the context of immune-mediated inflammatory diseases, notably life-threatening HLH and MAS. The question arises as to whether the two faces of etoposide action can apply to other topoisomerase II inhibitors.