대한흉부영상의학회 Korean Society of Thoracic Radiology

Discussion

Diagnosis With Brief Discussion

Diagnosis

Pulmonary Paragonimiasis

Radiologic Findings

Chest PA (not shown) showed slight increased interstitial lung markings on right lower lung zone. CT shows focal lobular air-space consolidation adjacent to the pleura in medial basal segment of right lower lobe. There is slight low density of central portion within the consolidation. Lung window setting shows ground glass opacities and faint centrilobular nodules on right middle and lower lobes. Slightly decreased volume of right lower lobe is seen. There are no pleural effusion and no mediastinal lymph node enlargement.

Eggs of Paragonimus westermani were found in bronchoalveolar lavage and stools. Skin test for Paragonimus westermani was positive. This patient had history of frequent ingestion of undercooked crabs.

Brief Review

Paragonimiasis is caused by the Paragonimus westermani through the ingestion of raw or partially cooked freshwater crabs or crayfish infected with the metacercaria. The main endemic areas are East Asia, Southeast Asia, Latin America, and Africa. Patients usually present with fever, chest pain, and respiratory symptoms such as chronic cough and hemoptysis. The penetration of juvenile worms through the diaphragm into the pleural cavity can cause pleural effusion or pneumothorax. Patchy air-space consolidation can occur, a phenomenon that reflects the presence of an exudative or hemorrhagic pneumonia that can be cavitated. Worm cysts, whose diameters range from 0.5 to 1.5 cm, are better visualized after the consolidation resolves and manifest as either solitary or multiple nodules or gas-filled cysts depending on their content and their communication with the airway. Sometimes clinical presentation and radiologic findings may be indistinguishable from pulmonary tuberculosis. Pulmonary infiltrates in paragonimiasis are poorly defined consolidation that changes rapidly with time, where as infiltrates in tuberculosis are nodular lesions that changes slowly. After treatment, residual fibrosis and emphysematous change are absent or minimal, whereas these findings are usual in tuberculosis. Subpleural linear opacities are unusual in tuberculosis.

References

1. Thoracic Manifestations of Tropical Parasitic Infections: A Pictorial Review. RadioGraphics. 2005 25:135-155.

2. Korean Society of Thoracic Radiology. Pulmonary Infections other than tuberculosis. In Korean Society of Thoracic Radiology. Thoracic Imaging 2000. Seoul: Seongmoonkak, 2000:123-129.

Keywords

Lung, Infection, Parasitic infection,