Secondary Hemophagocytic Lymphohistiocytosis in a Rocky Mountain Spotted Fever Patient.

Hemophagocytic lymphohistiocytosis (HLH) is a rare and potentially fatal hyperinflammatory syndrome caused by uncontrolled activation of cytotoxic T lymphocytes, natural killer (NK) cells, and macrophages, leading to cytokine storm and multiorgan dysfunction. Due to its nonspecific clinical presentation and high mortality, early recognition and multidisciplinary management are essential. We report the case of a 28-year-old woman admitted with fever, myalgias, arthralgias, and generalized exanthema. Initial laboratory evaluation revealed pancytopenia. Polymerase chain reaction (PCR) testing was positive for Rickettsia, and bone marrow examination demonstrated findings consistent with HLH. Despite appropriate management, the patient developed septic shock and died due to multiple complications, including multiorgan failure.