Pulmonary Paragonimiasis Initially Misdiagnosed, Leading to Delayed Diagnosis

Abstract

A 62-year-old asymptomatic man with a 25-pack-year smoking history underwent low-dose chest CT performed for a health screening. Initial low-dose chest CT revealed a 1-cm irregularly marginated nodule in the anterobasal segment of the right lower lobe, accompanied by multifocal ill-defined centrilobular nodules with a focal tree-in-bud appearance (Fig. 1, arrow). No pleural retraction or direct pleural attachment was observed. Laboratory findings were not significant, except for a positive QuantiFERON-TB test result. The peripheral eosinophil count was within the normal range and serological testing for Paragonimus spp. was negative. The dietary history of the patient regarding the ingestion of raw or undercooked freshwater food could not be obtained. Bronchoscopic biopsy revealed non-specific inflammation. As pulmonary tuberculosis was initially suspected, the patient underwent empirical anti-tuberculous therapy (6 months), followed by serial HRCT examinations at 6-month intervals, all of which revealed no significant interval change. The lack of interval changes over approximately 18 months did not support a diagnosis of active tuberculosis or malignancy. Twenty months later, follow-up contrast-enhanced chest CT images showed mini-Received