Severe Fever With Thrombocytopenia Syndrome: An Autopsy-Proven Case With Radiologic-Pathologic Correlation

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging tick-borne viral infection that can rapidly progress to multiple organ failure with a high mortality rate. Pulmonary involvement has been reported, but the radiologic-pathologic correlation remains poorly understood. We report an autopsy-proven fatal case of SFTS in a 79-year-old man with pre-existing collagen vascular disease-associated interstitial lung disease. Serial chest computed tomography (CT) initially demonstrated subtle peripheral ground-glass opacities that progressively expanded over time. On the final CT examination obtained shortly before death, extensive bilateral consolidation with high attenuation on mediastinal window images was observed, suggestive of pulmonary hemorrhage. The patient developed severe thrombocytopenia, disseminated intravascular coagulation, and respiratory failure and died despite intensive treatment. Autopsy revealed diffuse pulmonary hemorrhage, alveolar septal thickening, focal diffuse alveolar damage with hyaline membrane formation, and prominent hemophagocytosis. Immunohistochemical staining demonstrated numerous SFTS virus-infected cells within the lung tissue. This case highlights the CT findings of pulmonary involvement in fatal SFTS and demonstrates a direct radiologic-pathologic correlation. Our findings suggest that cytokine storm and hemophagocytic syndrome play critical roles in the development of pulmonary hemorrhage and lung injury in SFTS.