Case #401 – August 2015

A worm approximately three centimeters long was observed and removed during a routine colonoscopy of a 54-year-old man from Scandinavia. The worm was sent to the CDC-DPDx Team for identification. Figure A shows the gross worm at 10x magnification using a dissecting microscope. It was then cleared with lacto-phenol and examined at 100x magnification (Figures B and C show the anterior and posterior respectively). A thin cross-section was made and examined at the same magnification (Figure D) and 200x (Figure E). What is your diagnosis? Based on what criteria?

Figure A

Figure B

Figure C

Figure D

Figure E

This was a case of anisakiasis caused by Anisakis sp. The main diagnostic features shown in the images were:

presence of three lips (Figure B).
presence of Y-shaped lateral chords (black arrow, Figure E) and intestinal cells with a single basal nucleus (blue arrow, Figure E) and a brush border.

Figure B

Figure E