Metastatic Cancer – Melanoma
Histopathology of Melanoma
Lyz Boyd and Jennifer Kong
Learning Objectives
At the end of this section, you will be able to:
- Identify common histopathological features of melanoma.
- Determine whether the cancer is contained vs invading based on the basement membrane.
Before viewing these next videos on the histopathology of melanoma, please recall that:
- Cancerous changes are seen histologically by nuclear changes.
- Whether cancer is contained (i.e. localized) or invading depends on whether it has crossed the basement membrane.
- Metastasis can be determined if the primary cancer is found in distant structures. Metastasis can’t be diagnosed from the original site.
Critical Thinking & Histopathology Exercises
Answer the following questions for yourself before viewing the following videos.
- Melanocytes are few in number compared to keratinocytes. What would melanoma look like on low power magnification?
- Recall the cellular basis of cancer and what is happening at the DNA level. How would that look in nuclei stained with H&E?
- Cancer is known for uncontrolled growth. What would you expect to be the size of the cell undergoing cancerous changes? What would make that cell be bigger? smaller?
- Cancerous tissues are known to be at different levels of differentiation. What would that look like when looking at thousands of cells on low magnification vs dozens of cells on high power magnification?
- Whether a cancer spreads depends on whether it invades the basement membrane. What would that look like in low power magnification?
Histopathology of Melanoma- Smaller Magnification
Malignant Melanoma (Low Power) – DHPLC eslide PATH 425-249 by Lyz Boyd, licensed under All rights reserved
Histopathology of Melanoma – Greater Magnification
Malignant Melanoma (High Power) – DHPLC eslide: PATH 425-249 by Lyz Boyd, licensed under All rights reserved
Section Review
- Melanoma is identifiable by an abnormal number and collection of melanocytes compared to its normal distribution among keratinocytes.
- Common cancerous changes in melanocytes include:
- Nuclei of different sizes with very little cytosol.
- Cells in different sizes and stages of differentiation and cellular division.
- Melanoma is considered invasive if the abnormal growth of melanocytes has breached the basement membrane separating the epidermis and the dermis. Should these abnormal melanocytes be in close proximity to the blood vessels and lymphatics of the dermis & hypodermis, metastasis can occur.
Review Questions
