대한흉부영상의학회 Korean Society of Thoracic Radiology

Discussion

Diagnosis With Brief Discussion

Diagnosis

Pulmonary Sparganosis

Radiologic Findings

Fig 1. Chest PA shows an oval-shaped mass-like consolidation with satellite small nodules in the right middle lung zone.
Fig 2-5. CT scans reveal tubular soft tissue density obliterating superior segmental bronchus and small peribronchial nodular infiltration in the RLL superior segment. Also, focal bronchiectasis and bronchial wall thickening are observed in the RLL.

Brief Review

The patient underwent diagnostic bronchoscopic biopsy, revealing findings of chronic active inflammation with eosinophils. Subsequent analysis of a parasite-specific antibody test showed positive Sparganum-specific antibody IgG. Following a three-week course of praziquantel, a chest PA X-ray demonstrated significant improvement in consolidation within the right middle lung zone.

Sparganosis is a rare parasitic infection in humans caused by the larvae of a tapeworm belonging to the Spirometra genus. While adult spargana reside in the intestines of dogs and cats, their eggs are released into freshwater and hatch into coracidia, which are then consumed by copepod crustaceans. Within the copepod, coracidia develop into procercoid larvae, serving as the primary intermediate host. Infected copepods are later ingested by secondary intermediate hosts, such as birds, reptiles, and amphibians, where procercoids mature into plerocercoids. Human infection occurs through the consumption of untreated water containing infected copepods or by ingesting raw or undercooked secondary intermediate hosts, such as the flesh of snakes or frogs infected with plerocercoid larvae. The plerocercoid larvae have the potential to invade the intestinal wall, travel beneath the peritoneum, and migrate into various tissues, including subcutaneous tissue, muscles, and, rarely, the central nervous system, eyes, lungs, or pleura.
On CT images, lesions commonly distributed in the lower part of the lung, showing tortuous tunnel structure, suspected to be the parasite migration path with centrilobular nodular lesions and surrounding ground-glass opacifications. On 75% of the patients, pleural effusion or hydropneumothorax can be seen.

References

1. Mitsuru Matsuki, Akira Higashiyama. Pulmonary Sparganosis: Tunnel Sign and Migrating Sign on Computed Tomography. Internal medicine 2021 Feb 15; 60(4): 601–604
2. Sang Wan Chung, Yee Hyung Kim, Eun Jung Lee, Dae Hyun Kim, Gou Young Kim. Two cases of pulmonary and pleural sparganosis confirmed by tissue biopsy and immunoserology. Braz J Infect Dis 16 (2) Apr 2012

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