Giardia lamblia infection diagnosed by endoscopic ultrasound-guided fine-needle aspiration

The protozoan Giardia lamblia is a major cause of gastrointestinal disease worldwide. We report the case of a 59-yr-old male who presented to his primary care physician with complaints of abdominal pain and weight loss. Imaging studies revealed a liver mass and a pancreatic head mass. Biopsy of the liver mass proved to be benign, and endoscopic ultrasound-guided fine-needle aspiration of the mass in the head of the pancreas showed no evidence of malignancy; however, numerous pear-shaped, binucleated, flagellated organisms morphologically consistent with trophozoites of Giardia lamblia were identified in the specimen. With the increasing use of endoscopic ultrasound-guided fine-needle aspiration for sampling of gastrointestinal, hepatobiliary, and pancreatic lesions, cytopathologists examining such specimens will need to be familiar with the diagnostic characteristics of this protozoal parasite.