Background: Severe fever with thrombocytopenia syndrome (SFTS) is an emerging tick-borne zoonotic disease characterized by a high fatality rate of 12% to 15%. Despite hematologic abnormalities being frequently reported in SFTS patients, detailed characterization of peripheral blood cells, especially in severe cases, is scarce. This case report aims to fill this gap by describing the unique morphological features of blood cells in a patient with a severe outcome.

Methods: A male patient presented with severe symptoms of SFTS, including high fever and thrombocytopenia, and was subsequently infected with a highly virulent strain of the SFTS virus. Methods: The patient was diagnosed with virus-associated hemophagocytic syndrome related to SFTS based on clinical presentation and laboratory findings. Methods: The interventions included comprehensive supportive care and treatment aimed at managing the severe symptoms and complications associated with SFTS.

Results: Despite the interventions, the patient experienced significant morphological changes in white blood cells and ultimately succumbed to the illness.

Conclusions: The detailed description of abnormal cell morphology in this case provides valuable insights into the pathophysiology of SFTS. Recognizing these morphological abnormalities can aid in early detection and may have implications for assessing disease severity and guiding treatment strategies.