대한흉부영상의학회 Korean Society of Thoracic Radiology

Discussion

Diagnosis With Brief Discussion

Diagnosis

Scrub typhus

Radiologic Findings

Fig 1. Chest radiograph shows bilateral diffuse ground-glass and reticular opacities in both lungs.
Figs 2-5. Lung window images of chest CT demonstrate bilateral diffuse interlobular septal thickening involving both lungs, accompanied by subpleural ground-glass opacities and areas of consolidation predominantly in both lower lobes. In addition, several subpleural nodules with peripheral GGO halos in right lung.
Figs 6-7. Mediastinal window images of contrast-enhanced chest CT demonstrate enlarged bilateral mediastinal lymph nodes and focal splenic infraction.

Brief Review

He presented to the emergency department with a fever unresponsive to empiric antibiotic therapy. Two weeks prior to admission, he had a history of visiting a mountainous area for grass cutting. On physical examination, a diffuse maculopapular rash was noted over the skin, and an eschar was identified at the right iliac crest.
For definitive diagnosis, polymerase chain reaction testing for Orientia tsutsugamushi was performed and yielded a positive result. The patient was subsequently treated with doxycycline and azithromycin, after which both clinical symptoms and radiologic findings showed marked improvement.
Scrub typhus is an acute febrile illness caused by Orientia tsutsugamushi. The main pathologic change is focal or disseminated vasculitis caused by the destruction of endothelial cells and the perivascular infiltration of leukocytes. The diagnosis of scrub typhus is based on the patient’s history of exposure, clinical features, and results of serologic testing.
The pulmonary manifestations of scrub typhus include interstitial pneumonia, interstitial edema, and hemorrhage caused by vasculitis. Imaging typically demonstrates interstitial pneumonitis, characterized by bilateral ground-glass opacities, interlobular septal thickening, and patchy areas of consolidation, often with subpleural and lower lung predominance. Pleural effusions, centrilobular nodules, and mediastinal lymphadenopathy may also be present. In severe cases, pulmonary manifestations can progress to acute respiratory distress syndrome.
Abdominal manifestations include splenomegaly, periportal edema, gallbladder wall thickening, and lymphadenopathy. Less commonly, ascites, bowel wall thickening, and splenic infarction can be seen in severe cases. A high degree of clinical suspicion and familiarity with the various radiologic manifestations of scrub typhus allow early diagnosis and timely initiation of appropriate therapy, and thereby may help reduce patient morbidity.

References

1. Jeong YJ, Kim S, Yeh DW, Lee JW, Kim K-I, Lee SH. Scrub typhus: clinical, pathologic, and imaging findings. Radiographics 2007; 27(1): 161-172

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