Skin cancers

Summary

This script educates on skin cancer, detailing its types: basal cell carcinoma, squamous cell carcinoma, and melanoma. It explains the skin's structure, how melanin protects from UV damage, and the genetic and environmental causes of skin cancer. The script outlines symptoms, the importance of early detection, and various treatment options, emphasizing the role of UV exposure in cancer development.

Takeaways

• 📚 Learning medicine can be simplified with tools like Osmosis, which offer personalized study plans, videos, practice questions, and flashcards.
• 🌞 Skin cancer is an uncontrolled growth of skin cells, with three main types: basal cell carcinoma, squamous cell carcinoma, and melanoma.
• 🏥 Bob Marley's death from melanoma highlights that some skin cancers can be fatal if they spread to other parts of the body.
• 🧬 The skin is composed of three layers: the epidermis, dermis, and hypodermis, each with distinct functions and cell types.
• 🔬 Keratinocytes, filled with the protein keratin, protect the skin and are produced in the stratum basale, the deepest layer of the epidermis.
• 🌈 Melanocytes in the skin produce melanin, which determines skin color and acts as a natural sunscreen by scattering UV light.
• 🚨 Skin cancer can develop from DNA mutations in proto-oncogenes or tumor suppressor genes, leading to uncontrolled cell division.
• 📈 The progression from precancerous lesions like actinic keratosis to invasive squamous cell carcinoma illustrates the potential for skin damage to escalate.
• 🔍 The ABCDE rule (Asymmetry, Border, Color, Diameter, Evolving) helps identify suspicious melanoma lesions that require medical attention.
• 🌡 UV exposure is the leading environmental cause of skin cancer, with risk increasing as sun exposure accumulates over a lifetime.
• 🩺 Definitive diagnosis of skin cancer is made through tissue biopsy, with treatment options including surgery, cryotherapy, radiation, chemotherapy, or immunotherapy.

Q & A

What are the three main types of skin cancer mentioned in the script?

The three main types of skin cancer mentioned are basal cell carcinoma, squamous cell carcinoma, and melanoma.

What is the role of melanin in skin protection?

Melanin acts as a natural sunscreen by dissipating or scattering UVB light, which can damage the DNA in skin cells and potentially lead to skin cancer.

How does a tumor develop in the context of skin cancer?

A tumor develops if there's a DNA mutation in any of the skin cells that leads to uncontrolled cell division, typically due to mutations in proto-oncogenes or tumor suppressor genes.

What is the difference between benign and malignant tumors?

Benign tumors stay well contained or localized, while malignant tumors break through their basement membrane and invade nearby tissues, potentially metastasizing to other parts of the body.

Why are basal cell carcinomas less likely to metastasize compared to other skin cancers?

Basal cell carcinomas tend to be slow-growing tumors that can be locally invasive but rarely metastasize to distant regions of the body.

What is actinic keratosis and how is it related to squamous cell carcinoma?

Actinic keratosis is a precancerous lesion that can turn into squamous cell carcinoma. It involves damaged keratinocytes that over-produce keratin due to radiation damage.

How does melanoma differ from other skin cancers in terms of growth and risk?

Melanoma grows both horizontally within the epidermis and superficial dermis, and vertically, invading the dermis. It is the most aggressive and deadly form of skin cancer due to its tendency to metastasize quickly.

What are some environmental and genetic factors that can cause skin cancer?

Environmental factors include UV exposure from the sun or tanning booths, while genetic factors, viral infections like human papillomavirus, immunosuppression, and having light skin can also increase the risk.

What does the acronym ABCDE stand for when identifying melanoma?

ABCDE stands for Asymmetrical shape, Border irregularities, Color variation, Diameter larger than a pencil eraser, and Evolution or change over time.

What are some treatment options for skin cancer?

Treatment options include surgical removal, cryotherapy, radiation therapy, chemotherapy, and immunotherapy. Precancerous cells may also be treated with photodynamic therapy.

How is a definitive diagnosis of skin cancer typically made?

A definitive diagnosis of skin cancer is typically made through a tissue biopsy.

Outlines

00:00

🧬 Skin Cancer and Its Cellular Biology

This paragraph introduces the complexity of learning medicine and the utility of Osmosis for simplifying the process. It then delves into the topic of skin cancer, explaining the three main types: basal cell carcinoma, squamous cell carcinoma, and melanoma. The paragraph describes the layers of the skin, focusing on the epidermis and its cellular components, including keratinocytes and melanocytes. It discusses the role of melanin as a natural sunscreen and how DNA mutations in skin cells can lead to the development of skin cancer. The paragraph also explains the difference between benign and malignant tumors, and the process of metastasis.

05:02

🌞 Understanding Skin Cancer Types and Their Progression

The second paragraph continues the discussion on skin cancer, focusing on the progression and characteristics of squamous cell carcinoma and melanoma. It describes the early stages of squamous cell carcinoma, known as actinic keratosis and Bowen’s disease, and how they can evolve into more invasive forms. The paragraph also covers the aggressive nature of melanoma, its growth patterns, and its high potential for metastasis. The causes of skin cancer, including genetic and environmental factors such as UV exposure, are also discussed. The paragraph concludes with the signs and symptoms of different types of skin cancer and the various treatment options available, such as surgery, cryotherapy, radiation, chemotherapy, and immunotherapy.

Keywords

💡Skin Cancer

Skin cancer refers to abnormal growths or tumors that develop from the skin's cells. It is a critical theme in the video as it discusses the different types and their characteristics. The video mentions three main types: basal cell carcinoma, squamous cell carcinoma, and melanoma. Understanding skin cancer is vital as it can be deadly if not treated, especially when it metastasizes.

💡Epidermis

The epidermis is the outermost layer of the skin, composed mainly of keratinocytes. It plays a crucial role in protecting the body from environmental factors. In the video, the epidermis is highlighted as the starting point for the development of skin cancer, particularly where keratinocytes are involved.

💡Melanin

Melanin is a pigment produced by melanocytes that determines skin color and provides some protection against UV radiation. The video explains that melanin acts as a natural sunscreen, scattering UVB light, which can lead to skin cancer if not absorbed or reflected. It is particularly relevant to melanoma, the most aggressive form of skin cancer.

💡Keratinocytes

Keratinocytes are the primary cells in the epidermis, filled with the protein keratin, which provides strength and protection. The video describes how these cells mature and move upwards through the epidermal layers, flattening as they go. They are involved in basal cell carcinoma, the most common type of skin cancer.

💡Melanocytes

Melanocytes are cells in the skin that produce melanin. They are found in the stratum basale of the epidermis and at the base of hair follicles. The video mentions that melanocytes can be the source of melanoma, the deadliest form of skin cancer, and are also responsible for the formation of moles.

💡Metastasis

Metastasis is the process by which cancer cells spread from the original tumor to other parts of the body. The video emphasizes that the potential for metastasis increases with the depth of tumor invasion, making it a critical factor in determining the severity and treatment of skin cancer.

💡Proto-oncogenes

Proto-oncogenes are normal genes that can become oncogenes, leading to cancer when mutated. The video uses the analogy of an accelerator for proto-oncogenes, suggesting they can promote cell division when mutated, contributing to uncontrolled cell growth and tumor formation.

💡Tumor Suppressor Genes

Tumor suppressor genes are responsible for inhibiting cell division and preventing uncontrolled growth. The video likens them to brakes, and when they are mutated or nonfunctional, cells can divide uncontrollably, leading to tumors. This is a key concept in understanding how skin cancer develops.

💡Basal Cell Carcinoma

Basal cell carcinoma is the most common type of skin cancer, originating from cells in the stratum basale. The video describes it as slow-growing and locally invasive but less likely to metastasize. It is an example of how different skin cancers can have varying levels of severity and treatment requirements.

💡Squamous Cell Carcinoma

Squamous cell carcinoma involves squamous keratinocytes and can develop from precancerous lesions like actinic keratosis. The video explains that it can become invasive, breaking through the basement membrane and extending into the dermis, increasing the risk of metastasis.

💡Melanoma

Melanoma is the most aggressive and deadliest form of skin cancer, involving melanocytes. The video points out that it can grow both horizontally and vertically, invading deeper layers of the skin, and has a high tendency to metastasize quickly, making early detection and treatment crucial.

Highlights

Osmosis offers a personalized study plan with exclusive educational resources for medical students.

Skin cancer is an uncontrolled growth of cells within the skin, with three main types: basal cell carcinoma, squamous cell carcinoma, and melanoma.

Skin cancer can be fatal, as exemplified by Bob Marley's death shortly after being diagnosed with melanoma.

The skin is composed of three layers: the epidermis, dermis, and hypodermis, each with distinct functions.

Keratinocytes, filled with the protein keratin, protect the skin from damage.

Melanocytes in the skin produce melanin, which acts as a natural sunscreen against UV radiation.

DNA mutations in skin cells can lead to the development of skin cancer.

Basal cell carcinoma is the most common type of skin cancer, originating from cells in the stratum basale.

Squamous cell carcinoma can develop from precancerous lesions called actinic keratosis.

Melanoma is the most aggressive form of skin cancer, originating from melanocytes and has a high tendency to metastasize.

UV exposure is the leading environmental cause of skin cancer, with increased risk associated with sun exposure over a lifetime.

Skin cancer typically appears on sun-exposed skin, with different presentations for basal cell carcinoma, actinic keratosis, and squamous cell carcinoma.

Melanoma can be identified by the ABCDE rule: Asymmetry, Border irregularity, Color variation, Diameter larger than a pencil eraser, and Evolution over time.

A tissue biopsy is required for a definitive diagnosis of skin cancer.

Treatment options for skin cancer include surgery, cryotherapy, radiation, chemotherapy, and immunotherapy.

Precancerous cells are often removed to prevent progression to skin cancer.

The risk of developing skin cancer is influenced by genetic and environmental factors.

Transcripts

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Skin cancer is an uncontrolled growth of cells within the skin.

There are three main types: basal cell carcinoma, squamous cell carcinoma, and melanoma.

Some skin cancers can spread to other locations in the body and can be fatal, as seen with

singer-songwriter Bob Marley, who died shortly after being diagnosed with melanoma.

The skin is divided into three layers--the epidermis, dermis, and hypodermis.

The hypodermis is made of fat and connective tissue that anchors the skin to the underlying

muscle.

Just above is the dermis, which contains hair follicles, nerves and blood vessels.

And just above that, the outermost layer of skin, is the epidermis.

The epidermis itself has multiple cell layers that are mostly keratinocytes - which are

named for the keratin protein that they’re filled with.

Keratin is a strong, fibrous protein that allows keratinocytes to protect themselves

from getting destroyed, when you rub your hands through the sand at the beach.

Keratinocytes start their life at the deepest layer of the epidermis called the stratum

basale, or basal layer, which is made of a single layer of small, cuboidal to low columnar

stem cells that continually divide and produce new keratinocytes that continue to mature

as they migrate up through the epidermal layers, flattening out to a pancake-like squamous

shape as they ascend.

But the stratum basale also contains another group of cells - melanocytes, which secrete

a protein pigment, or coloring substance, called melanin.

Melanin is actually a broad term that constitutes several types of melanin found in people of

differing skin color.

These subtypes of melanin range in color from black to reddish yellow and their relative

quantity and rate at which they are metabolized define a person’s skin color.

When keratinocytes are exposed to the sun, they send a chemical signal to the melanocytes,

which stimulates them into making more melanin.

The melanocytes move the melanin into small sacs called melanosomes, and these get taken

up by newly formed keratinocytes, which will later metabolize the melanin as they migrate

into higher layers of the epidermis.

Melanin then acts as a natural sunscreen, because its protein structure dissipates,

or scatters, UVB light--which if left unchecked can damage the DNA in the skin cells and lead

to skin cancer.

Melanocytes can also be found in the dermis, at the base of the hair follicle, where they

transfer melanin to the keratinized cells that make up hair.

Now, a tumor develops if there’s a DNA mutation in any of these cell types that leads to uncontrolled

cell division.

Typically these are mutations in proto-oncogenes which result in a promotion of cell division,

or mutations in tumor suppressor genes which result in a loss of inhibition of cell division.

You can think of proto-oncogenes as the accelerator or gas pedal and tumor suppressor genes as

the brakes.

Too much acceleration or an inability to brake can lead to runaway cell division.

As a result, the mutated cells can start piling up on each other and can become a tumor mass.

Some of these tumors are benign and stay well contained or localized.

But some become malignant tumors or cancers, and these are the ones that break through

their basement membrane and invade nearby tissues.

Malignant tumor cells can get into nearby blood or lymph vessels, and travel from the

primary site to establish a secondary site of tumor growth somewhere else in the body

- and that’s called metastasis.

Skin cancer is differentiated based upon the type of skin cell that’s involved in the

tumor mass.

The most common is basal cell carcinoma, which involves cells in the stratum basale.

These tend to be slow growing tumors that can be locally invasive, but rarely metastasize

to distant regions of the body.

Nearby blood vessels in the dermis can become dilated to deliver more nutrients as the tumor

grows.

Basal cell carcinomas can grow superficially, spreading over several centimeters of the

epidermis.

And they can break through the basement membrane and invade the dermis, forming islands or

cords of tumor cells.

Tumor cells on the periphery of islands typically arrange themselves in a line, like fence-posts,

forming a palisading pattern.

The second most common type of skin cancer is squamous cell carcinoma which involves

squamous keratinocytes.

Now, a precancerous lesion that can turn into squamous cell carcinoma is called actinic

keratosis.

In an actinic keratosis, keratinocytes are damaged by radiation and begin to over-produce

keratin.

Over time, these damaged keratinocytes can develop into squamous cell carcinoma.

An early stage of squamous cell carcinoma is also called Bowen’s disease or squamous

cell carcinoma in situ.

At this point, the tumor can be found in the epidermis, but it has not broken through the

basement membrane.

Tumor cells are atypical – enlarged and over pigmented.

As squamous cell carcinoma becomes more invasive, it can break through the basement membrane

and extend into the dermis.

It may even reach the hypodermis, at which point it is more likely to metastasize.

Tumor cells at these more advanced stages typically vary in their degree of maturity,

have abnormal shapes, and over-produce keratin forming ‘pearls’.

Finally, the most aggressive form of skin cancer is melanoma which involves melanocytes.

Now, melanocytic nevus, more commonly known as a mole, results from a type of melanocyte

that over-produces melanin.

These moles can be considered precancerous because they carry an increased risk of becoming

a melanoma.

Melanomas grow horizontally within the epidermis and superficial dermis; and they grow vertically

- invading the dermis.

Metastasis is most associated with the depth of invasion, and in fact, melanoma is the

most deadly form of skin cancer because of its tendency to metastasize quickly.

Typically, the tumor cells have a large nuclei with irregular contours, and produce melanin

in a variety of colors: brown, red, dark blue, and gray.

The causes of skin cancer can be both genetic and environmental.

By far, the leading environmental factor is UV exposure from the sun or tanning booths.

Often, the risk of developing skin cancer increases as sun exposure over a lifetime

accumulates.

Some viral infections, like human papillomavirus; immunosuppression; and having light skin also

tend to increase risk.

Skin cancer typically appears on skin that’s exposed to the sun.

Basal cell carcinomas can appear as well-circumscribed, pearly, waxy, or shiny solid elevation of

skin.

They can also be ulcerated and red or pigmented.

Actinic keratosis can appear as dry, rough, almost sandpaper-like patches that are surrounded

by tan, brown, red or flesh colored skin.

They tend to commonly form on the lips, face, scalp, arm, ears, and the back of the hands.

Squamous cell carcinoma can appear as small, well-circumscribed, red elevations of the

skin with scaly plaques on top, which can sometimes ulcerate.

Moles can appear as small; oval; tan, pink, black, or brown spots that can be flat or

elevated.

Finally, the worrisome signs of melanoma can be remembered using the mnemonic ABCDE where

lesions are asymmetrically shaped, borders are irregular or notched, coloration varies

within the same lesion, the diameter is larger than the size of a pencil eraser, and the

lesion rapidly evolves over time and can cause skin elevation.

These lesions may also be itchy or painful.

A tissue biopsy is needed to make a definitive diagnosis of skin cancer, and treatment options

include removal with surgery or with cryotherapy, where the tumor is frozen off.

Radiation, chemotherapy or immunotherapy may also be options.

And precancerous cells, like in actinic keratosis or melanocytic nevus, are typically removed

to prevent their progression to skin cancer with cryotherapy or photodynamic therapy,

which is where light is used to induce cellular death.

So, to recap: there are three main types of skin cancer: the most common, basal cell carcinoma;

the second most common, squamous cell carcinoma; and the most deadly, melanoma – and they

all form from uncontrolled growth of cells within the epidermal layer of the skin.

Tumors can remain relatively contained, or invade other layers of the skin.

The deeper the tumor invades, the greater the risk of metastasis.

UV exposure is a risk factor, so areas of the face and body exposed to the sun are particularly

affected, like the scalp; lips; ears; arms; and the backs of the hands.

Diagnosis is made with a tissue biopsy and treatments can include physically removing

cells with a high risk of developing into skin cancer.

Tumor cells are also commonly removed and treated with radiation, chemotherapy, or immunotherapy.