science

Histopathology of colorectal adenocarcinoma

Histopathology of colorectal adenocarcinoma is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Histopathology of colorectal adenocarcinoma rather than just read about it. In short: The histopathology of colorectal cancer of the adenocarcinoma type involves analysis of tissue taken from a biopsy or surgery. A pathology report contains a description of the microscopical characteristics of the tumor tissue, including both tumor cells and how the tumor invades into healthy tissues and finally if the tumor appears to be completely removed.

Key takeaways

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Reference excerpt

The histopathology of colorectal cancer of the adenocarcinoma type involves analysis of tissue taken from a biopsy or surgery. A pathology report contains a description of the microscopical characteristics of the tumor tissue, including both tumor cells and how the tumor invades into healthy tissues and finally if the tumor appears to be completely removed. The most common form of colon cancer is adenocarcinoma, constituting between 95% and 98% of all cases of colorectal cancer. Other, rarer types include lymphoma, adenosquamous and squamous cell carcinoma. Some subtypes have been found to be more aggressive.

Macroscopy Cancers on the right side of the large intestine (ascending colon and cecum) tend to be exophytic, that is, the tumor grows outwards from one location in the bowel wall. This very rarely causes obstruction of feces, and presents with symptoms such as anemia. Left-sided tumors tend to be circumferential, and can obstruct the bowel lumen, much like a napkin ring, and results in thinner caliber stools.

Microscopy Adenocarcinoma is a malignant epithelial tumor, originating from superficial glandular epithelial cells lining the colon and rectum. It invades the wall, infiltrating the muscularis mucosae layer, the submucosa, and then the muscularis propria. Tumor cells describe irregular tubular structures, harboring pluristratification, multiple lumens, reduced stroma ("back to back" aspect). Sometimes, tumor cells are discohesive and secrete mucus, which invades the interstitium producing large pools of mucus. This occurs in mucinous adenocarcinoma, in which cells are poorly differentiated. If the mucus remains inside the tumor cell, it pushes the nucleus at the periphery, this occurs in "signet-ring cell." Depending on glandular architecture, cellular pleomorphism, and mucosecretion of the predominant pattern, adenocarcinoma may present three degrees of differentiation: well, moderately, and poorly differentiated. Micrographs (H&E stain)

Microscopic criteria

A lesion at least "high grade intramucosal neoplasia" (high grade dysplasia) has: Severe cytologic atypia Cribriform architecture, consisting of juxtaposed gland lumens without stroma in between, with loss of cell polarity. Rarely, they have foci of squamous differentiation (morules). This should be distinguished from cases where piles of well-differentiated mucin-producing cells appear cribriform. In such piles, nuclei show regular polarity with apical mucin, and their nuclei are not markedly enlarged. Invasive adenocarcinoma commonly displays: Varying degrees of gland formation with tall columnar cells Frequently desmoplasia Dirty necrosis, consisting of extensive central necrosis with granular eosinophilic karyorrhectic cell detritus. It is located within the glandular lumina, or often with a garland of cribriform glands in their vicinity.

Subtyping

Determining the specific histopathologic subtype of colorectal adenocardinoma is not as important as its staging (see #Staging section below), and about half cases do not have any specific subtype. Still, it is customary to specify it where applicable.

Differential diagnosis Colorectal adenocarcinoma is distinguished from a colorectal adenoma (mainly tubular and ⁄or villous adenomas) mainly by invasion through the muscularis mucosae. In carcinoma in situ (Tis), cancer cells invade into the lamina propria, and may involve but not penetrating the muscularis mucosae. This can be classified as an adenoma with "high-grade dysplasia", because prognosis and management are essentially the same.

Grading Conventional adenocarcinoma may be graded as follows

Staging

Staging is typically made according to the TNM staging system from the WHO organization, the UICC and the AJCC. The Astler-Coller classification (1954) and the Dukes classification (1932) are now less used. T stands for tumor stage and ranges from 0, no evidence of primary tumor, to T4 when the tumor penetrates the surface of the peritoneum or directly invades other organs or structures. The N stage reflects the number of metastatic lymph nodes and ranges from 0 (no lymph node metastasis) to 2 (four or more lymph node metastasis), and the M stage gives information about distant metastasis (M0 stands for no distant metastasis, and M1 for the presence of distant metastasis). A clinical classification (cTNM) is done at diagnosis and is based on MRI and CT, and a pathological TNM (pTNM) classification is performed after surgery. The most common metastasis sites for colorectal cancer are the liver, the lung and the peritoneum.

Tumor budding Tumor budding in colorectal cancer is loosely defined by the presence of individual cells and small clusters of tumor cells at the invasive front of carcinomas. It has been postulated to represent an epithelial–mesenchymal transition (EMT). Tumor budding is a well-established independent marker of a potentially poor outcome in colorectal carcinoma that may allow for dividing people into risk categories more meaningful than those defined by TNM staging, and also potentially guide treatment decisions, especially in T1 and T3 N0 (Stage II, Dukes' B) colorectal carcinoma. Unfortunately, its universal acceptance as a reportable factor has been held back by a lack of definitional uniformity with respect to both qualitative and quantitative aspects of tumor budding.

Immunohistochemistry In cases where a metastasis from colorectal cancer is suspected, immunohistochemistry is used to ascertain correct diagnosis. Some proteins are more specifically expressed in colorectal cancer and can be used as diagnostic markers such as CK20 and MUC2. Immunohistochemistry can also be used to screen for Lynch syndrome, a genetic disorder with increased risk of colorectal and other cancers. The diagnosis of Lynch syndrome is made by looking for specific genetic mutations in genes MLH1, MSH2, MSH6, and PMS2. Immunohistochemical testing can also be used to guide treatment and assist in determining the prognosis. Certain markers isolated from the tumor can indicate specific cancer types or susceptibility to different treatments.

References

Illustrations

Worked examples

Example 1 — a first encounter with Histopathology of colorectal adenocarcinoma

Start with the simplest possible case. Write down what Histopathology of colorectal adenocarcinoma claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Histopathology of colorectal adenocarcinoma before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Histopathology of colorectal adenocarcinoma ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Histopathology of colorectal adenocarcinoma

In research: Histopathology of colorectal adenocarcinoma appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Histopathology of colorectal adenocarcinoma in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Histopathology of colorectal adenocarcinoma is common in secondary-school and first-year university syllabi. It links to neighbouring topics Colorectal cancer, Histopathology, so understanding it makes those chapters shorter.
In everyday life: Look for Histopathology of colorectal adenocarcinoma outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Histopathology of colorectal adenocarcinoma in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Histopathology of colorectal adenocarcinoma means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
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Frequently asked questions

What is Histopathology of colorectal adenocarcinoma in simple terms?

Why does Histopathology of colorectal adenocarcinoma matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Histopathology of colorectal adenocarcinoma?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Histopathology of colorectal adenocarcinoma.