This conference centers on a healthy young guy with fever, cough, myalgias, diarrhea, bilateral lower-lobe pulmonary infiltrates, terminal ileitis, cytopenias, transaminitis, severe inflammation, rhabdomyolysis, and hyperferritinemia. His outdoor exposures, tick risk, positive Lyme IgM, and clinical deterioration prompted consideration of tick-borne illness, viral triggers, and other causes of secondary HLH. The case highlights how “tick-looking labs” such as leukopenia, thrombocytopenia, and transaminitis can overlap with HLH, and how a positive Lyme screening result may distract from more plausible HLH triggers.
The teaching portion provides a practical review of HLH as a hyperinflammatory Th1/macrophage activation syndrome, including diagnostic clues, H-score interpretation, infectious triggers, and the role of steroids versus treatment of the underlying infection. The talk emphasizes intracellular pathogens as common infectious triggers, reviews the literature on tick-borne HLH, and contrasts organisms commonly associated with HLH—such as ehrlichiosis, anaplasmosis, babesiosis, rickettsial infections, and EBV—with Lyme disease, which is presented as an unlikely explanation for the HLH phenotype.