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Imaging Diagnosis

Pulmonary Paragonimiasis

Many series describing the radiographic characteristics of hundreds of cases of paragonimiasis have been reported, primarily from the Orient. A characteristic pattern exists in which pleural and parenchymal exudative reactions, nodule and cyst formation, and eventually fibrosis and occasional calcifications are seen, depending on the stage and severity of the disease. Im et al described the radiological findings in 71 patients with pleuropulmonary paragonimiasis in a 1992 report (Table 22.1). They and other investigators in Korea (Chung 1971) and Taiwan (Yang et al) have divided paragonimiasis into three distinct clinical and radiological stages:

Table 22.1 - Findings on chest radiographs in 71 patients with pleuropulmonary paragonimiasis

Finding _____________________________________________No. of Patients (%)

Pulmonary lesions
Air-space consolidation
Focal patchy 32 (45)
Segmental lobar 5 (7)
Subtotal 37 (52)
Cyst(s) 33 (46)
Linear opacity 29 (41)
Nodule 18 (25)
Total 59 (83 a
Pleural lesions
Unilateral 20 (28)
Bilateral 6 (8)
Subtotal 26 (37)
Unilateral 6 (8)
Bilateral 6 (8)
Subtotal 12 (17)
Thickening 5 (7)
Total 43 (61)
a Total represents total number of patients with pulmonary lesions, not total number of findings.


The Stage of Migrating Larvae. Clinical manifestations may first be noted a month or more after infection. Subcutaneous creeping tumors, chest or abdominal pain, cough (often with blood-streaked sputum) and general malaise can be seen during this stage, which may last 3 to 12 months.

Radiographically, this initial larval migrating period, when the flukes penetrate the diaphragm to enter the pleural cavity (see Fig.22.7A), is characterized by pleural effusion (Fig.22.12) and/or pneumothorax.


Fig. 22.12A-D. Pleural reactions in three adult Korean men with paragonimiasis. (A) There is marked pleural thickening and fluid along the right lateral chest wall, costophrenic angle, and base. There is also a small patchy area of infiltrate at the left base, partially obscuring the lateral aspect of the left hemidiaphragm. Several small ring-like cavities less than 1 cm in size are present in the left second anterior interspace and left and right lower lung fields. P. westermani eggs were identified in the sputum. A right carotid arteriogram and a pneumoencephalogram demonstrated a large right parietal mass that was an intracerebral cyst caused by the parasite (see Fig. 22.40). Pleural fluid or thickening together with migratory patchy infiltrates are common in the initial migrating larval phase of the disease. Later the classic ring-like cavities can be identified in the lungs, together with small burrows or tracts left by the worms. (Courtesy of Dr. William Harshaw, Oakton, Virginia.) (B) There is pleural thickening or fluid at the right costophrenic angle in another patient with paragonimiasis who also has a small 1-cm cavitary lesion in the lateral aspect of the right midlung immediately above a slightly thickened minor pleural fissure. (C) There is a small pleural effusion at the left base and costophrenic angle in a North Korean man who had chest pain, cough with bloody sputum, and poor appetite of 40 days duration. Dry rales were heard on auscultation. He also had a small transient infiltrate in the right midlung on the initial chest film. (D) A follow-up chest film shows only minimal residual pleural reaction at the left costophrenic angle, but there is now a small 1.5 cm nodular density in the lateral aspect of the left lung base immediately above the diaphragm representing the mature worm phase of the disease. Localized pleural thickening or effusion is commonly seen in association with the peripheral nodules or cysts of paragonimiasis.

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