Mediastinal cysts associated with Paragonimus westermani

Abstract

•Paragonimiasis can rarely manifest as a mediastinal cystic mass.•Paragonimiasis can be transmitted to the mediastinum in the absence of pulmonary lesions.•Surgical resection can aid in the diagnosis and treatment of mediastinal paragonimiasis. A 48-year-old man presented to the thoracic surgery clinic with an incidentally detected mediastinal mass on chest radiography (Figure 1a). He was asymptomatic with no relevant medical history. Laboratory studies showed normal leukocyte and eosinophil counts. Magnetic resonance imaging revealed multilocular cystic lesions (6 × 4.5 cm) with abscess formation in the pericardial space (Figure 1b-d). The first impression was multilocular thymic cysts. The cysts were removed by uniportal video-assisted thoracic surgery (Figure 2). Histologic analysis revealed a multicystic lesion with central necrosis and peripheral granulomas with parasitic eggs in the thymus (Figure 3). He was diagnosed with Paragonimus westermani infection. P. westermani can be transmitted by eating infected raw freshwater crabs [[1]Harinasuta T Pungpak S Keystone JS. Trematode infections. Opisthorchiasis, clonorchiasis, fascioliasis, and paragonimiasis.Infect Dis Clin North Am. 1993; 7: 699-716https://doi.org/10.1016/S0891-5520(20)30550-XAbstract Full Text PDF PubMed Google Scholar], and it mainly presents as subpleural consolidations, pneumothorax, and pleural effusion [[2]Singh TS Mutum SS Razaque MA. Pulmonary paragonimiasis: clinical features, diagnosis and treatment of 39 cases in Manipur.Trans R Soc Trop Med Hyg. 1986; 80: 967-971https://doi.org/10.1016/0035-9203(86)90275-0Abstract Full Text PDF PubMed Scopus (74) Google Scholar]. It is extremely rare that paragonimiasis presents as multilocular cysts in the mediastinum without pulmonary manifestation. He enjoyed eating raw crab marinated in soy sauce, and it is speculated that the larvae migrated through the diaphragm and made an abscess pocket in the anterior mediastinum. At the 15-month follow-up visit after surgical removal and medication of praziquantel, he showed no evidence of recurrence. When presented with unexplained mediastinal multilocular cysts, paragonimiasis can be included in the differential diagnosis.Figure 2Intraoperative observation of a cystic lesion of the anterior mediastinum.View Large Image Figure ViewerDownload Hi-res image Download (PPT)Figure 3Histologic findings of (a) central necrosis and peripheral granulomas (b) with parasitic eggs in the thymus.View Large Image Figure ViewerDownload Hi-res image Download (PPT) The authors have no competing interests to declare.