Skin Cancer
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The short, high energy wavelength of UV light can cause the DNA of skin cells to mutate. This will often produce cells that will divide in an uncontrolled manner. Light-skinned people are most susceptible to this type of cancer.
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Go to File, Open Samples and open the image N1. This image shows a surface view of a mole. A mole is a pigmented, congenital skin blemish. They can become cancerous and have to be watched for changes.
1. What is meant by the term congenital? If this pigmented area occurs on the head, neck and hands and tends to repeatedly bleed and crust over it is probably a basal cell carcinoma. (A carcinoma is a cancer that tends to develop from the skin and basal refers to it originating from the base of the epidermal skin layer.) This is the most common of the skin cancers. When the developing cells of the epidermis rise to the surface, they flatten out and are referred to as squamous cells.
(The cheek cells you examined the first of the school year are squamous cells.) These red scaly patches or nodules are the second most common form of cancer and are typically found in the facial area. While basal cell carcinomas are typically benign (remain in place), squamous cell carcinomas will metastazie (spread). Leave N1 open Go to File, Open Samples and open the image M1. This new file shows a melanoma. These skin cancers make up only 1% of the total but cause the majority of deaths. They are referred to as malignant melanomas and arise from the melanocyte cells that produce much of your skin coloration.
Open Samples and open the image Skin_Stk.
This is a model of a skin section. Use the sliders on the image to move back
and forth between the labeled and unlabeled images. Fat cells (Adipose
Tissue) cushions the skin layer and insulates the body. The Dermis is
filled with connective tissue containing a number of different glands and structures
that exit to the outside. It has an extensive blood supply. The Epidermis consists
of cells that are being produced in a regular fashion and migrate to the surface.
As they migrate they flatten out (B) and by the time they have reached (C) they
are flat and called squamous epithelial cells. The basal cells are found at
(A) - base of the epidermis -and the melanocytes are found in the same region
bordering the dermis. Melanoma
Close Skin_Stk and Go to File,
Open Samples and open the image Mel_Stk. There are five images in this stack. The first image is a microscopic section of the human skin with several of the structures labeled. Based on the model and your reading you should be able to see the relationship between these skin areas very readily. The basal layer (from which new epithelial cells arise) is located at the very base or bottom of the epidermal layer. It is also here that we find the melanocyte cells that produce the pigment melanin. Move the slider ahead to file 2/5 of the stack and you will find the same image without the labels. See if you can correctly identify the different parts. Move on to 3/5. This image is
another section on the same microscope slide of the patient.
3. Is it the same magnification? Explain. An enlargement of the dermal area is shown in 4/5.
4. How does this enlargement compare with the previous example in respect to magnification and area being shown? Explain.What we have here are and in Figure 3/5 are melanocyte cells that have multiplied and have penetrated down further into the skin. Finally we have image 5/5 which is the same magnification as 4/4 except it is showing a capillary. (You can vaguely see squamous epithelial cells making up the single cell wall of a capillary with red blood cells inside.)
5. Right now -Figure 3/5 -this melanoma is in situ, -- what is the concern ?Extra Credit (Information on how to calibrate/measure an image is found on Calibrate in the image samples.)
1. In the Mel_Stk if the magnification is 200X in 3/5, what is the magnification in 5/5? Show your labeled calculations.
2. Measure 5 red blood cells and determine their average diameter? Show labeled work.
3. In 5/5 why would the the cells making-up the capillary be squamous epithelial cells and not cells cuboidal or columnar in shape?
4. Open File T2 which is in the Extra Credit folder. The structure that the ? is pointing at is located in what layer of the skin? This black material is not normally found in the skin but is more commonly found in the skin. What is it? Explain.
ReferenceThe follow are WEB reference sites for information on Skin Cancer
Melanoma.Com - Your source for information on Skin Cancer and its Treatment
An Introduction to Skin Cancer A general introduction to Skin Cancer, with links to specific information available around the Net.
Guide to Internet Resources for Cancer Skin cancer is the most common type of cancer and accounts for half of all new cancers in Western populations
How to recognize a melanoma YOU CAN BE AN EXPERT AT DIAGNOSING MELANOMA
Results
(You can also Go to File, Open Samples and Open the image Results which is a copy of this Results section. While this page cannot be printed out - at this time - it can be saved as a JPEG file to your desktop. You can then open it with any graphics program,type out the answers and then print it out from your program. You can also enter the results on this image using the Text
Tool. To do this first go to Edit, Options, Fonts and select something like Geneva - 12 pt - Bold. Then click on the Results Image in the answer space and draw out the yellow rectangle that appears and start typing. When you are finished go to Edit and Select Draw. What you have typed should now be present.)
1. What is meant by the term congenital?
2. Compare the two images and list the ways the malignant melanoma is "different" from the benign mole. Use your text as a reference.
3. Are they the same magnification? Explain.
4. How does this enlargement compare with the previous example in respect to magnification and area being shown?
5. Right now -Figure 3/5 -this melanoma is in situ, -- what is the concern ?
