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PBL Giardia.pptx
- 1. Problem based learning Duodenal biopsy of 21 years/Male Presenter: Dr. Rajya Khadka Pathology resident 1st year Moderator: Dr Om Jha
- 2. Case History • Age - 21 years • Sex – Male • Chief complain – Pain abdomen - Diarrhea • 1 H&E stained slide received
- 12. Slide description • Section shows three bits of duodenal mucosa with maintained crypt to villi architecture with focal villous blunting. Mucosa is lined by simple columnar epithelium with interspersed goblet cells in the epithelial lining • Lamina propria contains mixed inflammatory infiltrates comprising of predominantly lymphocytes along with few plasma cells and eosinophils • Submucosa comprises of multiple Brunner glands • Luminal surface shows multiple pear shaped as well as sickle shaped structures likely trophozoites of Giardia lamblia • No atypia or features of malignancy seen
- 13. Diagnosis • Giardiasis Differential diagnosis • Amebiasis • Cryptosporidosis • Celiac disease
- 14. Favouring points • Clinical history • Site • Morphology of organism • Size of organism is similar to enterocyte nuclei Unfavouring points • No villous blunting • No increase in IEL (Intraepithelial lymphocytes ) Giardia lamblia
- 15. Giardia lamblia • Also known as Giardia duodenalis/intestinalis • G. lamblia is the most common protozoal pathogen in humans and is spread by fecally contaminated water or food • Spreads by fecally contaminated water, common in underdeveloped countries • Infection may occur after ingestion of as few as 10 cysts • Attaches to mucosa but does not invade • Cause decreased expression of brush-border enzymes, microvillous damage, and apoptosis of small intestinal epithelial cells • Evade immune clearance through continuous modification of the major surface antigen, variant surface protein & can persist for months or years, causing intermittent symptoms • May cause endoscopic duodenal nodularity
- 16. Life cycle Person swallows contaminated food, water with Giardia cyst ↓ Cyst in small intestine releases two trophozoites through excystation ↓ Trophozoites multiply into two longitudinal binary fission ↓ Remain in small intestine in free or attached to lining of the small intestine ↓ Trophozoites move toward colon and transform into cyst through encystation ↓ Giardia cyst stage most commonly seen in stool • Both Giardia cysts & trophozoites can be found in stool of person with giardiasis and may be observed microscopically • Giardia cysts are immediately infectious when passed in stool or shortly afterward & cysts can survive several months in cold water or soil
- 17. Diagnosis • Microscopic diagnosis Detection of cysts, trophozoites in stools by direct saline, iodine wet preparations and use of concentration technique like formal ether Often, multiple stool specimens need to be examined In asymptomatic carriers - only cysts are seen Fixed stool smear can be stained with trichrome to identify cysts and trophozoites • Enterotest (String test) - obtaining duodenal specimen to detect parasites • Molecular diagnosis -PCR on stool specimen • Trophozoites immunoreactive for the protooncogene KIT (C-kit, CD117) • Brush cytology – because the organism are on the luminal surfaces of the intestinal epithelial cells (flat, gray, pear shaped & binucleate with four pairs of flagella) • Duodenal biopsy
- 18. Microscopic findings • Duodenal biopsy- trophozoites have characteristic pear shape and the presence of two equally sized nuclei • Despite large numbers of trophozoites, some of which are tightly bound to the brush border of villous enterocytes, there is no invasion & small intestinal morphology may be normal • Villous blunting with increased numbers of IELs & mixed lamina propria inflammatory infiltrates can accompany heavy infections • Absence/ marked decrease of plasma cells in the lamina propria in a patient with giardiasis - possibility of an underlying immunodeficiency disorder • Although Giardia is characteristically described as a small bowel inhabitant, colonization of the stomach and colon has also been reported
- 20. Amebiasis • Causative organism- Entaemoeba histolytica • Cecum followed by the right colon, rectum, sigmoid &appendix • Grossly, small ulcers are seen initially, but these may coalesce to form large, irregular, geographic or serpiginous ulcers & may undermine adjacent mucosa to produce classic “flask- shaped” lesions • Histologically, early lesions show a mild neutrophilic infiltrate • In some cases, numerous organisms are present at the luminal surface with little associated inflammation • In advanced disease, ulcers are often deep extending into the submucosa with undermining of adjacent normal mucosa with usually abundant necroinflammatory debris, which in many cases exceeds the amount of associated inflammation. • The organisms are usually found in the purulent material • Invasive amebae are also occasionally present in the bowel wall • Adjacent mucosa is usually normal but may show gland distortion • They resemble macrophages, with foamy cytoplasm and round, eccentric nuclei. The presence of ingested red blood cells is pathognomonic (erythrophagocytosis)
- 21. Cryptosporidosis • Transmission is through contaminated food and water, and person-to-person spread via the fecal-oral route • Most common in the small bowel in the crypts or in the surface epithelium but may infect any segment of the GI tract • Characteristic biopsy appearance is that of a 2- 5 um, basophilic, spherical body that protrudes from the apex of enterocyte • Known as “blue beads” due to their round, basophilic appearance • Associated mucosal changes include villous atrophy (occasionally severe), crypt hyperplasia, mixed inflammation, and crypt abscesses
- 22. Celiac disease/ Gluten-sensitive enteropathy/Sprue • Advanced celiac disease - completely flattened mucosa, with total loss of villi, such that the duodenum mimics colon • Absorptive epithelium loses its brush border and flattens into a low cuboidal layer resulting in malabsorption • Earliest and most subtle change is prominent intraepithelial lymphocytes (IELs) at the tips of the villi, even before there is noticeable villous blunting • Over 40 IELs/100 enterocytes (with a single villus being approximately equal to 100 enterocytes) is considered diagnostic of a malabsorption pattern
- 23. Approach to duodenal biopsy • Normal duodenal mucosa - 1 mm thick - narrow villi that project above the mucosal surface - between the villi, tube-like crypts which invaginate down into the mucosa • Epithelium is intestinal type - goblet cells interspersed among the absorptive cells • Lamina propria- Lymphocytes, plasma cells & eosinophils • Few intraepithelial lymphocytes (IELs) but rare at the tips of the villi • Submucosa - Brunner glands, which stain bright pink • Proximal duodenum – Brunner glands. Distalmost duodenum/jejunum/ileum)- devoid of Brunner glands
- 24. At low power • Assess the height of the villi. In a well-oriented specimen, they should be greater than three times as tall as the crypts are deep. • Villous blunting/atrophy - short and stubby villi (villi don’t get shorter instead crypts & surrounding mucosa get deeper • Total thickness of mucosa remains same • Areas of epithelium darker than surrounding mucosa – suggestive of dysplasia or any mass lesion
- 25. At high power • Intraepithelial lymphocytes (IELs) - tips of villi indicating celiac disease • Peptic duodenitis - Neutrophils in the epithelium & gastric (foveolar type) metaplasia • Immunodeficiency state - no plasma cells in lamina propria
- 26. Clinical history required for interpretation of biopsy • Age and sex of the patient • Signs and symptoms, site of the biopsy, endoscopic findings, radiological findings • Clinical diagnosis or impression • Medical and surgical history • History of taking drugs or alcohol • History of immunosuppression • Findings of previous biopsies
- 27. Indications for a duodenal biopsy • Evaluation of patients with malabsorption • Investigation on patients with iron‐deficiency anaemia • Diagnosis or monitoring of gluten‐sensitive enteropathy (GSE) • Diagnosis of neoplasia • Investigation on patients with diarrhoea, particularly in patients in whom infection is suspected (AIDS) • Confirmation of ulceration induced by non‐steroidal anti‐inflammatory drugs (NSAIDs) or in cases of bleeding from an unknown site
- 28. Biopsy report should include • Number and site of the biopsy specimens - at least three specimens in distal duodenum • Villous height and architecture: normal, broad or blunted? • Normal villous to crypt (V:C) ratio (range from 3:1 to 5:1) • Presence of crypt hyperplasia • Surface enterocytes: normal, flattened or damaged • Brush borders: preserved or lost • IEL count • Gastric metaplasia in chronic duodenitis • Presence of microorganisms: Giardia, cryptosporidia, microsporidia, Isospora belli, cyclospora, Mycobacterium avium intracellulare, cytomegalovirus, Cryptococcus neoformans • Neoplasia: presence of benign or malignant tumour (adenoma or carcinoma, carcinoid, lymphoma)
- 29. References • Aster, K. A., 2020. Robbins & Cotran Pathologic Basis of Disease. Tenth Edition ed. s.l.:Elsevier. • Rosai, J., Ackerman, L., Goldblum, J., Lamps, L., McKenney, J. and Myers, J., 2018. Rosai and Ackerman's surgical pathology. Philadelphia: Elsevier. • Robert D. Odze, J. R. (Third edition). Odze and Goldblum Surgical Pathology of the GI Tract, Liver, Biliary Tract and Pancreas. Elsevier.
Editor's Notes
- Zoomastigophora Stool usually contains cysts (can also be detected by immunofluorescent technique)
- Parasite mistaken for cytoplasmic debris Giemsa & trichome with iron hematoxylin stain KIT / CD117 may be useful for diagnosis
- Giardia duodenalis is a protozoan flagellate (Diplomonadida) Secretory IgA and mucosal IL-6 responses are important for clearance of Giardia infections. Immunosuppressed, agammaglobuinemic, or malnourished individuals are often severely affected. Giardia can evade immune clearance through continuous modification of the major surface antigen, variant surface protein, and can persist for months or years, causing intermittent symptoms. This protozoan was initially named Cercomonas intestinalis by Lambl in 1859. It was renamed Giardia lamblia by Stiles in 1915 in honor of Professor A. Giard of Paris and Dr. F. Lambl of Prague. However, many consider the name Giardia duodenalis to be the correct taxonomic name for this protozoan. Affects 1/3 of homosexual men in urban communities May cause endoscopic duodenal nodularity (Indian J Pathol Microbiol 2011;54:312) Causes epithelial barrier dysfunction by down regulating claudin1 and increasing epithelial apoptoses
- Giardia cysts can contaminate food, water, and surfaces, and they can cause giardiasis when swallowed in this infective stage of their life cycle. Infection occurs when a person swallows Giardia cysts from contaminated water, food, hands, surfaces, or objects. When Giardia cysts are swallowed, they pass through the mouth, esophagus, and stomach into the small intestine where each cyst releases two trophozoites through a process called excystation. TheGiardia trophozoites then feed off and absorb nutrients from the infected person. Giardia trophozoites multiply by splitting in two in a process called longitudinal binary fission, remaining in the small intestine where they can be free or attached to the inside lining of the small intestine. The Giardia trophozoites then move toward the colon and transform back into cyst form through a process called encystation. The Giardia cyst is the stage found most commonly in stool. Both Giardia cysts and trophozoites can be found in the stool of someone who has giardiasis and may be observed microscopically to diagnose giardiasis. Giardia cysts are immediately infectious when passed in the stool or shortly afterward, and the cysts can survive several months in cold water or soil. .
- t may be difficult to distinguish amebae from macro- phages in inflammatory exudates. However, amebae are trichrome- and PAS-positive, and macrophages stain with immunostains such as CD68 and CD163. In addition, amoeba nuclei are usually more round and pale, with a more open nuclear chromatin pattern. The differential diagnosis of amebiasis includes Crohn’s disease, ulcerative colitis, and other types of infectious colitis, particularly when gross skip lesions or significant architectural distor- tion is present. Although some features of amebiasis may mimic idiopathic IBD, many of the other diagnostic fea- tures of Crohn’s disease (e.g., transmural lymphoid aggre- gates, mural fibrosis, granulomas, neural hyperplasia) and ulcerative colitis (e.g., basal lymphoplasmacytosis, diffuse architectural distortion, pancolitis) are not typically present in amebiasis.
- Giemsa and Gram stains may aid in diagnosis, and immunohistochemical antibodies are available. Cryptosporidia may be distinguished from most other coccidians by their size and unique apical location
- Keep in mind that the differential for these histologic findings is long and is only diagnostic of celiac disease if the serology and clinical picture agrees.
- Duodenum is included here as duodenal biopsies often accompany upper GI in biopsy specimens, and the pathology in some cases is continuous. A duodenal biopsy may be performed because of combined gastritis and duodenitis, with or without peptic ulcer disease; to investigate suspected malabsorption syndromes, such as celiac disease; or to diagnose a mass lesion.
- Critter check – look for the fallen leaves of Giardia or the clinging dark bubbles of Cryptosporidium, both easy to miss. Strongyloides is hard to miss. Are there abundant stuffed histiocytes in the lamina propria? Some microorganisms are primarily found inside histiocytes. The earliest and most subtle change is prominent intraepithelial lymphocytes (IELs) at the tips of the villi, even before there is noticeable villous blunting. Over 40 IELs/100 enterocytes (with a single villus being approximately equal to 100 enterocytes) is considered diagnostic of a malabsorption pattern. Also keep in mind that the differential for these histologic findings is long and is only diagnostic of celiac disease if the serology and clinical picture agrees. i