Giardia Is Often Overlooked on Histopathologic Examination: A High-Volume, Single-Institution Experience

Minqian Shen, Lysandra Voltaggio, Scott Robertson

Research output: Contribution to journalArticlepeer-review

Abstract

Aims. Giardia: is sometimes missed by the pathologist, and we sought to determine how often this occurs at our institution—a large tertiary care center with a subspecialty gastrointestinal pathology service and what certain clinical and histologic clues can be used to flag cases with a higher likelihood of infection, targeting them for greater scrutiny. Methods and Results: We identified a set of patients who tested positive for Giardia with a stool-based test, and who also received a small bowel biopsy at a similar time-point. These biopsies were retrospectively reviewed for Giardia, finding 8 positive cases. The organism was prospectively detected in 4 cases (50%) but overlooked in the remaining 4 cases (50%). Three of the 4 cases missed cases showed only rare organisms. The detected cases tended to more frequently have prominent lymphoid aggregates (3 detected cases, 0 overlooked cases) and intraepithelial lymphocytosis (3 detected cases, 0 overlooked cases). Certain clinical and histologic clues can be used to flag cases with a higher likelihood of infection. Specifically, we found abnormalities of the mucosa (active inflammation, intraepithelial lymphocytosis, villous expansion, prominent lymphoid aggregates) in each case, and 4 of 8 cases were from immunocompromised patients. Finally, 2 of 8 cases were terminal ileum biopsies. Conclusions: Biopsies with a histologic abnormality or those from immunocompromised patients should receive greater attention. Routinely looking for Giardia at that terminal ileum is necessary.

Original languageEnglish (US)
Pages (from-to)257-262
Number of pages6
JournalInternational journal of surgical pathology
Volume29
Issue number3
DOIs
StatePublished - May 2021
Externally publishedYes

Keywords

  • Giardia lamblia
  • duodenum
  • immunodeficiency
  • infection
  • terminal ileum

ASJC Scopus subject areas

  • Surgery
  • Anatomy
  • Pathology and Forensic Medicine

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