d

Fig. 6.5 (continued)

Table 6.1 Common diseases manifesting as CT halo sign

Note: GGO ground-glass opacity, ANCA antineutrophil cytoplasmic antibody

usually minimal but could be severe, including low-grade fever, dry cough, substernal chest discomfort, dyspnea, wheezing, and blood-tinged sputum to frank hemoptysis. Blood and sputum eosinophilia is the most common laboratory abnormality.

CT Findings

Parasitic infestation most commonly results in Þndings similar to LoefßerÕs syndrome. Pulmonary visceral larva migrans such as Ascaris suum or Toxocara canis appears on CT as migrating multifocal subpleural nodules with halo of groundglass opacity and ill-deÞned margin (Fig. 6.1) [17]. Pleuropulmonary paragonimiasis usually manifests as a necrotic subpleural nodule with focal pleural thickening and subpleural streaky opacity connecting the pleura and the nodule. More than half of cases, this nodule has adjacent areas of ground-glass opacity [6].

CT–Pathology Comparisons

In cases of pulmonary visceral larva migrans, mutifocal subpleural nodules with a halo of ground-glass opacity are related to patchy interstitial thickening, an inßammatory exudate composed largely of eosinophils, and alveolar hemorrhage and edema [18]. In cases of pleuropulmonary paragonimiasis, subpleural nodule with a necrotic low attenuation is related to necrotic granuloma and organizing pneumonia [6].

Patient Prognosis

Antihelminthic therapy is necessary to eradicate the infection caused by Strongyloides, Ascaris, and Paragonimus. The role of antihelminthic agents in the treatment of Toxocara is not established.

Eosinophilic Lung Disease (Parasitic

Infestation)

Pathology and Pathogenesis

Secondary eosinophilic lung disease caused by parasites can manifest as simple, acute, chronic, or incidental eosinophilic pneumonia [15].

Symptoms and Signs

The most common parasitic infections for pulmonary eosinophilia are caused by Strongyloides, Ascaris, Toxocara,

Paragonimus, and Ancylostoma species [16]. Symptoms are

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