Case #259 – September, 2009

A four-year-old child was admitted to the hospital for sever abdominal pain mimicking appendicitis. A small section of bowel was removed and sent to the Pathology Department for work-up. A section of tissue was preserved in formalin, sectioned, and stained with hematoxylin and eosin (H&E). Images A–C show what was observed at 100x magnification of slides made from the tissue specimen. In addition to the biopsy, stool was collected for routine ova and parasite (O&P) examination. The object is Figure D, which measured on average 73 micrometers long by 37 micrometers wide, was seen in low numbers in a concentrated wet mount from a formalin-preserved aliquot of the stool. What is your diagnosis? Based on what criteria?

Figure A

Figure B

Figure C

Figure D

This was a case of hookworm infection caused by a member of the genus Ancylostoma or Necator. An examination of intact mouthparts of the adult or male sexual structures is necessary for genus-level identification. Diagnostic features included:

a longitudinal section of an adult hookworm in tissue demonstrating the oral cavity (OR, Figure A) and a strong, muscled esophagus (ES, Figure A).
cross-sections of an adult hookworm in tissue demonstrating platymyarian musculature (MU, Figure B), coiled ovaries (OV, Figure B), excretory ducts (ED, Figure B), and an intestine with a brush border (IN, Figure B).
partially-embryonated eggs in stool with a thin, hyaline shell and within the size range (60-75 micrometers long by 35-40 micrometers wide) for hookworm (Figure D).

Figure A

Figure B