Neoplasia Case Studies II


CASE 3: Familial polyposis of colon


History:

A 21-year-old man is found to have a stool specimen positive for occult blood, taken with rectal examination during a routine physical. He tells you that several relatives died from "cancer of the bowel" at an early age.

Image 3.1:

Describe the gross appearance of the colon (this patient had a similar disease). Multiple mass lesions are present. They are polypoid. The polyps are on long stalks. They are well-circumscribed.

Image 3.2:

Describe the microscopic appearance of this small polypoid lesion from the colon of this patient. The glands in this polyp are more crowded and have cells that are more hyperchromatic than the adjacent normal colonic mucosa of the stalk, but overall they are well-differentiated. This is a benign adenomatous polyp.

Images 3.3 and 3.4:

How does this microscopic appearance of a 4 cm mass lesion in the colon differ from the polyp in the last image? The glands are much more irregular and have less differentiation. This is adenocarcinoma of the colon.
  1. What further procedure(s) can be done to determine what his problem is?

    2. A colonoscopy could define the lesions present. Radiographic procedures may also help (barium enema).

  2. What are the genetics of neoplasia? Discuss oncogenes and tumor suppressor genes. What is happening in this case? What produces cell transformation?

    3. Some neoplasms are associated with oncogenes (e.g., the result of a genetic a point mutation to activate a ras oncogene, or a chromosomal translocation to activate a c-myc oncogene) and others with faulty tumor suppressor genes (anti-oncogenes) such as p53 in some colon, breast, lung, and liver neoplasms. A few tumors are even associated with faulty genes that allow excessive growth.

  3. What are tumor markers? Is such a marker useful in this case?

    4. Tumor markers are substances within or secreted by neoplasms that can be immunohistochemically or in serum. Colon cancers, for example, are associated with production of carcinoembryonic antigen (CEA). No marker is completely specific for a given tumor, nor are the markers always sensitive enough to detect all cases. Therefore, tumor markers are not useful as general screening tests in the general population. However, tumor markers can be applied in specific situations to help confirm a diagnosis or to follow up a patient after treatment.