The Differential Diagnosis of Artifacts in Biopsies of the Gastrointestinal
What is an artifact?
Houghton-Mifflin Dictionary on the Web, 2004:
|Artifact: a structure or feature not normally present but visible as a result of an external agent or action, such as one seen in a microscopic specimen after fixation, or in an image produced by radiology or electrocardiography. |
|An inaccurate observation, effect, or result, especially one resulting from the technology used in scientific investigation or from experimental error: The apparent pattern in the data was an artifact of the collection method.|
|A feature not normally present but visible as a result of an external agent or action, such as one seen in a microscopic specimen after fixation |
This discussion deals with artifacts, i.e., features not normally
present but visible as a result
of external agents or actions
in endoscopic biopsies of the gut.
There is a sequence of events involved in obtaining and processing a gut biopsy, and these events may
act as the external agents or actions mentioned above and alter the microscopic appearance of the
These events occur:
Some of these artifacts mimic real histologic changes in disease, so they have a differential
diagnosis. We have to determine if the biopsy changes are those of true disease, or if they are
Some of these artifacts so distort the histologic features that they lead to issues of adequacy of
biopsy: Do the artifacts prevent me from making a diagnosis; i.e., is the biopsy useless for diagnosis?
Differential Diagnosis #2
1. Sufficient for DX
2. Insufficient for DX
Before Endoscopy: The Preparation
Artifacts due to endoscopy preparations
|Hypertonic enemas (flex sigs, colons in kids)|
|Oral phosphosoda (colons in adults)|
Hypertonic enemas (flex sigmoids, colonoscopies in kids)|
|flattened surface epithelium|
|focal surface tufting|
|clumpy superficial hemorrhage|
|flattened surface epithelium focal surface tufting, confused with type 1 lesion of PMC edema|
|clumpy superficial hemorrhage, confused with ischemic hemorrhage|
Figure 2 - Enema effect |
Oral phosphosoda (colonsoscopies in adults):
|pseudo and true aphthous lesions|
|focal acute cryptitis|
Figure 3 - Endoscopic aphthous ulcer-like changes due to oral phosphosoda |
Focal acute inflammation may be an artifact that does not require diagnosis.
Oral phosphosoda is the main culprit.
Figure 4 - Oral phosphosoda artifacts |
Very Focal Acute Cryptitis/Pititis/Glanditis
|Common in gastrointestinal biopsies that are otherwise completely normal.|
|More common in teaching hospitals: require pathology residents|
During endoscopy: the endoscope itself
|obtaining the biopsy|
|retrieving the biopsy|
Air insufflation produces holes that mimic
Obtaining the biopsy
|Forceps—congestion, hemorrhage, crushing, squeezing, denudation of surface epithelium|
The forceps induced changes may mimic disease:
|Squeezing may leave a lamina propria devoid of crypt epithelium, mimicking ischemic injury.|
|Squeezing of Brunner's glands leads to the appearance of extravasated mucin and occasional confusion with signet ring carcinoma or lipid storage or Whipples disease|
|Crushing of the base of gastric can produce cells that resemble signet ring carcinoma cells.|
|Sometimes helpful, as when it marks the margin of resection of an adenoma with invasive carcinoma.|
|Sometimes not helpful, as when|
- An adenoma with carcinoma is removed piecemeal using cautery. Many pieces are cauterized, preventing identification of the margin of the entire lesion.
- An entire polyp is cauterized, thus preventing diagnosis
During processing: our fault
Artifacts that are our fault:
|Everything that we see on a microscopic slide is the result of a series of artifacts.|
|We depend on the reproducibility of these artifacts in order to make diagnostic decisions.|
|Fixation clots the proteins|
|Dehydration takes out the water|
|Organic solvents like xylene dissolve the lipids so we can't see them|
|Paraffin: since when is that a part of normal anatomy?|
|Then the paraffin-filled tissue is cut really thin so it will transmit light.|
|Hematoxylin? Eosin? Totally unnatural|
Tisssue preparation artifacts infrequently lead to changes that mimic diseases. A few examples:
|Different fixatives lead to different nuclear details: we all get used to our own fixatives|
|Peculiar bias cuts of small intestine can produce areas that look avillous (flat)|
|Tissue cut too thickly, leading to a false impression of dysplasia|
Many of these agents damage the tissue so severely that diagnosis is impossible.
|Forceps: Squeezing, crushing, stripping of surface epithelium|
|Inadequate fixation: dessicated|
|Shredding during cutting|
Trying to diagnose diseases in GI biopsies is tough enough, but we also have to
overcome artifacts, which make things even tougher.
- Driman DK, Preiksaitis HG: Colorectal inflammation and increased cell proliferation associated with oral sodium phosphate bowel preparation solution. Hum Pathol. 29:972-978, 1998
- Faigel DO, Furth EE, Bachwich DR. Aphthoid lesion of the rectum. Letter to the Editor. Gastrointestinal Endoscopy. 43:528-529, 1996. Documents the endoscopic aphthoid appearance of lymphoid follicles following oral phosphosoda.
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- Lee FD. Importance of apoptosis in the histopathology of drug related lesions in the large intestine. J Clin Pathol. 46:118-122, 1993
- Meisel JL, Bergman D, Graney D, Daunders DR, Rubin CE. Human rectal mucosa: proctoscopic and morphological changes caused by laxatives. Gastroenterol. 72:1274-1279, 1977
- Pockros PJ, Foroozan P. Golytely lavage versus a standard colonoscopy preparation. Effect on normal colonic mucosal histology. Gastroenterol. 88:545-548, 1985.
- Snover DC, Sandstad J, Hutton S. Mucosal pseudolipomatosis of the colon. Am J Clin Pathol. 84:575-580, 1985