대한흉부영상의학회 Korean Society of Thoracic Radiology

Discussion

Diagnosis With Brief Discussion

Diagnosis

Scrub Typhus (Tsutsugamushi disease)

Radiologic Findings

Initial chest radiograph shows increased interstitial opacities and reticular opacities in both lungs. Thin-section CT scan shows interlobular septal thickening, bronchovascular bundle thickening, and multifocal ground-glass opacities which are patterns of the interstitial pneumonia. On CT there are also minimal amount of bilateral pleural effusion and multiple, enlarged lymph nodes less than 2cm in mediastinum.

Brief Review

The patient had an eschar on her left calf on the physical examination. Her laboratory data showed positive Rickettsia antibody, mild LFT abnormality and hyponatremia.

Scrub typhus (tsutsugamushi disease) is an acute febrile illness caused by Orientia tsutsugamushi. It is transmitted to humans by the bite of mites or chiggers. Scrub typhus has epidemics in the late fall that affect a wide area of South-East Asia and the Pacific rim including the Korean Peninsula. Scrub typhus involves multiple organs including the lung, heart and central nervous system and is characterized by focal vasculitis or perivasculitis seceondary to direct endothelial injury.

The diagnosis of scrub typhus is based on history of exposure, clinical features and serological testing. The main clinical manifestations are high fever, chill, headache, skin rash, myalgia, lymph node enlargement and characteristic eschar formation. The latent period of the disease is 6 to 18 days. The clinical course is usually mild and self-limited with spontaneous recovery after a few days, but some patients have a more severe course which may be fatal.

The radiological findings of scrub typhus are variable, ranging from normal to fulminant pulmonary edema. On chest radiography, parenchymal abnormalities with lower lung predilection including bilateral reticulonodular opacities, groun-glass opacities, consolidation, septal lines and hilar lymph node enlargement, cardiomegaly and pleural effusions. On thin-section CT, ground-glass opacity with a gravitational distribution, bronchial wall thickening, intralobular septal thickening and centrilobular nodules which may reflect the interstitial pneumonia.

The differential diagnosis of scrub typhus is pulmonary interstitial edema and pulmonary interstitial pneumonia such as viral pneumonia, Mycoplasma pneumonia, and Pneumocystis Jiroveci pneumonia etc.

References

YH Choi, SJ Kim, JY Lee, HJ Pai, KY Lee, YS Lee. Scrub Typhus: Radiological and Clinical Findings. Clinical Radiology 2000; 55: 140?44

Keywords

Lung, Infection, Parasitic infection,