Abstract
A case of chronic anisakiasis presenting as an occluding duodenal tumor is described. Significant falls in Anisakis simplex-specific serum IgE and total IgE occurred after resection of the lesion. Histopathologic examination showed a chronic eosinophilic granulomatous infiltrate and a tubular sclerotic structure in the antral submucosa consistent with, but not diagnostic for, an A. simplex larva.