Table 2

 Common infections seen in the duodenum

GiardiasisCryptosporidiaMicrosporidiaCyclosporaIsosporaWhipple’s diseaseMAIVisceral leishmaniasisCryptococcosisCytomegalovirus
DPAS, diastase periodic acid Schiff; IEL, intraepithelial lymphocyte; MAI, Mycobacterium avium intracellulare; PAS, periodic acid-Schiff; /, not applicable.
Microorganism Giardia lamblia Cryptosporidium parvum Enterocytozoonbieneusi and Encephalitozoonintestinalis Cyclospora cayetanensis Isospora belli Tropheryma whippelii Mycobacterium avium intracellulare Leishmania donovani Cryptococcus neoformans Cytomegalovirus
VilliNormal or slightly flattenedShortened bluntedShortened bluntedShortened bluntedShortened bluntedShortened bluntedShortened bluntedShortened bluntedShortened bluntedUlcers and granulation tissue
CryptNormalMild hyperplasiaMild hyperplasiaMild hyperplasiaMild hyperplasiaNormalNormalNormalNormalVariably damaged
Lamina propriaNormal or mild increase in inflammationMild increase in lymphocytes, plasma cells and eosinophilsMild increase in lymphocytes, plasma cells and eosinophilsMild increase in lymphocytes, plasma cells and eosinophilsMild increase in lymphocytes, plasma cells and eosinophilsInfiltration of pale monocyte/macrophageInfiltration of pale macrophagesInfiltration of macrophagesMinimal or no inflammatory responseMixed inflammatory infiltrate
Lamina propriaIncrease in plasma cells and other chronic inflammatory cells
IELsNormal or increasedNormalNormalMildly increasedNormalIncreasedNormalNormalNormalMay be increased
Neutrophilic infiltrateRarelyFocalNoNoNoNoNoNoNoMay be present
Surface epitheliumNormalFocal degenerationFocal degenerationFocal degenerationFocal degenerationNormalNormalNormalNormalVariably damaged
Cells infectedNoneEnterocyteE bieneusi and E intestinalis: enterocytesEnterocytesEnterocytesMonocyteMacrophageMacrophagesNoneEndothelial, stromal and crypt epithelial cell
E intestinalis macrophagesMacrophageEndothelial, stromal and crypt epithelial cell
LocalisationAttached to the enterocytes along the villi, without invasionCrypt and surface epithelium along the brush borderE. bieneusi and E intestinalis on mainly villous tips, but not in the cryptVillous tipsAlong the villi but not in the cryptLamina propriaLamina propriaLamina propriaLamina propriaLamina propria
E intestinalis lamina propria
AppearancePear shaped cut lengthwise, binucleate, ventral disc (5×20–30 μm) with four pairs of flagellaMerozoites (2–5 mm) of varying size and basophiliaSupranuclear parasitophorous vacuoles indenting the nucleusRound and fusiform merozoites (up to 6 mm in length) in supranuclear parasitophorous vacuoleSubnuclear parasitophorous vacuole (20–30 mm) contains banana-shaped merozoites and sexual forms (T-sign)PAS positiveAcid fast and D-PAS-positive curved bacilli1–2 μm basophilic amastigotes in an identifiable parasitophorous vacuoleCryptococci, narrow neck budding“Owl’s eye” nuclear inclusion and basophilic, granular cytoplasmic inclusions
Ziehl–Nielsen-negative intracytoplasmic granules
StainsGiemsaWarthin StarryWarthin Starry: spores and microsporidia//PASPAS/D-PAS Methanamine silverImmunoperoxidase
Braun-Brenn gram: sporesZiehl–NielsenZiehl–Nielsen
Auramine