Pulmonary paragonimiasis

Last revised by Dr Daniel J Bell on 14 Jan 2020

Pulmonary paragonimiasis is a food-borne parasitic disease caused by the lung fluke (trematode) Paragonimus westermani. It is endemic in southeast Asia, the Far East, and is also relatively common in Latin America and Africa 1,2. The disease can affect both the lung and pleura 3, although lung parenchymal involvement is thought to be commoner than pleural involvement 2.

Radiographic features

CT chest: HRCT

It usually manifests as a poorly marginated subpleural or subfissural nodule of about 2 cm in diameter that frequently contains a necrotic low attenuation area 2. The constellation of focal pleural thickening and subpleural linear opacities leading to a necrotic peripheral pulmonary nodule is another frequent CT finding.

There are also a myriad of other associated non-specific features. These can vary with the stage of disease.

Early findings are thought to be caused by the migration of juvenile worms and include:

Later findings are thought to be caused by worm cysts and include:

Differential diagnosis

Imaging features can sometimes mimic that of lung cancer or pulmonary tuberculosis 2.

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