Case #146 - December, 2004

A 45-year-old man had coughing spells, typically in the morning, over a 2-year period. He decided to consult his primary care physician after noting blood in his sputum on a few occasions. The man said he did not have allergies but that he occasionally smoked cigars. He also mentioned that he traveled frequently for business to Asia and Africa. His physician requested a chest x-ray, and upon examination, cavitary lesions were observed in both lungs. A biopsy of lung tissue was obtained, sectioned, and stained with hematoxylin and eosin (H & E). Figure A shows what was observed in moderate numbers on the slide (200× magnification). What is your diagnosis? Based on what criteria?

Figure A

Answer to Case #146

This was a case of paragonimiasis caused by Paragonimus spp. Morphologic features seen in the images were:

the size of the egg, approximately 85 micrometers, which was in the size range for Paragonimus spp. eggs.
the presence of an operculum. This feature eliminates other helminth eggs in the same size range, Trichostrongylus, Ascaris (infertile), and Schistosoma japonicum.
location (lung tissue) where the eggs were found.

Identification to the species-level using egg morphology is difficult and interpretation in tissue sections is even more challenging. Patient travel history to Africa and Asia could mean he was infected with P. westermani or another of the Asian species, or one of several species found in Africa. Also there are reports of U.S. residents acquiring P. kellicotti locally, and in this case, the travel history is suggestive but possibly misleading. For these reasons, this case is probably best diagnosed as Paragonimus spp.