Hemophagocytic Lymphohistiocytosis Syndrome With Hepatic Involvement and Secondary to Acute B-cell Lymphocytic Leukemia: A Case Report.

Hemophagocytic lymphohistiocytosis (HLH) is a hyperactivation syndrome associated with the overactivation of macrophages, which produce enormous amounts of tumor necrosis factor-alpha and interferon-gamma. HLH often presents with diminished T-cell and natural killer (NK) cell regulation, which can develop due to underlying genetic causes, infections, autoimmune diseases, and/or secondary to malignancies. Here, we describe the case of a 39-year-old man who presented with subjective fevers and fatigue. Further workup revealed hyperferritinemia, hypertriglyceridemia, and absent NK-cell activity, which raised a strong suspicion for HLH. The workup also revealed elevated aminotransferases signaling hepatic involvement that was attributed to HLH. Bone marrow biopsy revealed hypercellularity instead of the hemophagocytosis usually seen in HLH. Flow cytometry revealed acute B-cell lymphocytic leukemia, which was identified as the cause of HLH in our patient. This case highlights the rare presentation of HLH secondary to a B-cell malignancy. It addresses the importance of high clinical suspicion in patients with high fevers despite the use of broad-spectrum antibiotics. There is limited information on the treatment of HLH secondary to malignancies specifically, and further research in this area is needed to increase the survival rate.

Acute Extensive Deep Vein Thrombosis After Heterogeneous Administration of Moderna mRNA Booster Vaccine: A Case Report.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) struck the world in 2019 and led to the development of the multisystem coronavirus disease-2019 (COVID-19) causing a worldwide pandemic. Vaccines with boosters were developed due to novel mutations of SARS-CoV-2. Heterogeneous vaccination emerged with the perception that mixing vaccines can provide better protection. We present the case of a 68-year-old male patient who developed extensive acute deep vein thrombosis (DVT) of the left lower extremity, two weeks following the Moderna mRNA booster vaccine (mRNA-1273). His first two doses were AstraZeneca ChAdOx1-S [recombinant]. He was started on a heparin drip and prescribed rivaroxaban. We discuss the possible etiology of this DVT, the mechanism of action of the Moderna mRNA vaccine, the association of DVT with vaccine-induced inflammation, implications of heterogeneous vaccine combinations, and recommendations to advise people on possible thrombogenic adverse effects prior to mRNA vaccine administration.