Hypereosinophilia with Hepatic Nodule Formation Caused by Ganoderma lucidum

A 61-year-old man who underwent surgery for rectal adenocarcinoma developed multiple hepatic nodules. The nodules were 1-3 cm without a capsular structure or contrast enhancement on computed tomography/magnetic resonance imaging, findings that were atypical for adenocarcinoma metastases. A biopsy showed the aggregation of eosinophils without larval bodies, ova, or granulomas. Laboratory tests showed a marked increase in eosinophils and a slight liver enzyme elevation. He had been taking the commercial herbal medicine Ganoderma lucidum for his liver function. After discontinuing G. lucidum, the eosinophil counts and liver enzyme levels rapidly resolved, and the nodules disappeared completely. This is a rare case of hypereosinophilia with hepatic nodules reactive to herbal medicine rather than a parasitic infection.