Case #195 - January, 2007

A patient complaining of intermittent symptoms including coughing up blood, fever, and other vague “flu-like” symptoms saw a physician. The patient reported working at a sushi restaurant and eating a raw crab on a dare (Figure A shows a crab similar to the one that the patient ate). Blood tests were ordered and results included peripheral eosinophilia of 10% and a history of bilateral pneumothorax (free air or gas in the pleural cavity). A biopsy yielded a cyst containing a structure 5 mm in length and 2 mm in width. Figure B (40×) and Figure C (100×) show a hematoxylin and eosin (H & E) stained section of the specimen. Figure D (400×) shows an object which measured 80-90 µm by 40-45 µm. Similar objects were found in low numbers in sections of lung tissue. What is your diagnosis? Based on what criteria?

Figure A

Figure B

Figure C

Figure D

Case Answer

This was a case of paragonimiasis caused by Paragonimus spp. Diagnostic features were:

the presence of oral and a ventral sucker (acetabulum), characteristic of trematodes (arrows, Figure B).
a thick tegument with spines (arrows, Figure C) on the surface, which is consistent with Paragonimus spp.
operculated eggs (Figure D) with prominent “shoulders” (arrows, Figure D) that were within the size range for Paragonimus spp.

The most common species in the genus known to infect humans is P. westermani. A species identification can be made if the entire, intact worm is examined, but even then an accurate assessment may still be difficult; accurate epidemiological data can also be helpful in attempting to determine the geographic origin of the infection. Serology and molecular testing can also be performed.