Chapter 6 - Section 6.4 - Study Guide - Assess Your Learning Outcomes - Page 199: 1

Skin cancer is a broad category of cancers that originate in the skin. There are three main types of skin cancer, each with distinct characteristics in terms of appearance, cell origin, frequency, and severity. These three forms of skin cancer are: **1. Basal Cell Carcinoma (BCC):** - **Appearance:** Basal cell carcinoma often appears as a raised, pearly bump that may have visible blood vessels. It can also manifest as a scaly, reddish patch or a sore that does not heal. Ulceration and crusting are common. - **Cell Origin:** BCC originates from the basal cells in the lowest layer of the epidermis (outermost layer of the skin). - **Frequency:** Basal cell carcinoma is the most common type of skin cancer. It accounts for approximately 80% of all skin cancer cases in the United States. - **Severity:** While BCC rarely spreads to other parts of the body (metastasizes), it can invade surrounding tissues if left untreated. Early diagnosis and treatment usually result in excellent outcomes. **2. Squamous Cell Carcinoma (SCC):** - **Appearance:** Squamous cell carcinoma often appears as a firm, red nodule or a flat sore with a scaly or crusty surface. It may resemble a wart or an open sore that does not heal. - **Cell Origin:** SCC originates from the squamous cells in the epidermis, which are found in the upper layers of the skin. - **Frequency:** Squamous cell carcinoma is the second most common type of skin cancer, accounting for about 20% of skin cancer cases. - **Severity:** SCC has a higher potential for spreading (metastasis) compared to BCC. If not treated promptly, it can invade nearby lymph nodes and tissues. Early detection and treatment are crucial for better outcomes. **3. Melanoma:** - **Appearance:** Melanoma often appears as an irregularly shaped mole or pigmented lesion. It may have asymmetrical borders, variations in color (multiple shades of brown, black, or red), and a diameter larger than a pencil eraser (usually larger than 6 mm). It can evolve and change in size, shape, or color over time. - **Cell Origin:** Melanoma originates from melanocytes, the pigment-producing cells in the epidermis. - **Frequency:** Melanoma is less common than BCC and SCC, but it is the most aggressive and potentially deadly form of skin cancer. It accounts for a smaller percentage of skin cancer cases but is responsible for the majority of skin cancer-related deaths. - **Severity:** Melanoma has a high potential for metastasis if not detected and treated early. Early diagnosis is crucial, as it can spread to other organs. However, when detected in its early stages, melanoma is often curable through surgical removal. In summary, the three main forms of skin cancer are basal cell carcinoma (BCC), squamous cell carcinoma (SCC), and melanoma. They differ in appearance, cell origin, frequency of occurrence, and severity. BCC and SCC are more common, generally less aggressive, and have a lower risk of metastasis compared to melanoma, which is less common but more aggressive and potentially lethal if not treated promptly. Regular skin examinations and early detection are essential for effective treatment and improved outcomes for all types of skin cancer.

Skin cancer is a broad category of cancers that originate in the skin. There are three main types of skin cancer, each with distinct characteristics in terms of appearance, cell origin, frequency, and severity. These three forms of skin cancer are: **1. Basal Cell Carcinoma (BCC):** - **Appearance:** Basal cell carcinoma often appears as a raised, pearly bump that may have visible blood vessels. It can also manifest as a scaly, reddish patch or a sore that does not heal. Ulceration and crusting are common. - **Cell Origin:** BCC originates from the basal cells in the lowest layer of the epidermis (outermost layer of the skin). - **Frequency:** Basal cell carcinoma is the most common type of skin cancer. It accounts for approximately 80% of all skin cancer cases in the United States. - **Severity:** While BCC rarely spreads to other parts of the body (metastasizes), it can invade surrounding tissues if left untreated. Early diagnosis and treatment usually result in excellent outcomes. **2. Squamous Cell Carcinoma (SCC):** - **Appearance:** Squamous cell carcinoma often appears as a firm, red nodule or a flat sore with a scaly or crusty surface. It may resemble a wart or an open sore that does not heal. - **Cell Origin:** SCC originates from the squamous cells in the epidermis, which are found in the upper layers of the skin. - **Frequency:** Squamous cell carcinoma is the second most common type of skin cancer, accounting for about 20% of skin cancer cases. - **Severity:** SCC has a higher potential for spreading (metastasis) compared to BCC. If not treated promptly, it can invade nearby lymph nodes and tissues. Early detection and treatment are crucial for better outcomes. **3. Melanoma:** - **Appearance:** Melanoma often appears as an irregularly shaped mole or pigmented lesion. It may have asymmetrical borders, variations in color (multiple shades of brown, black, or red), and a diameter larger than a pencil eraser (usually larger than 6 mm). It can evolve and change in size, shape, or color over time. - **Cell Origin:** Melanoma originates from melanocytes, the pigment-producing cells in the epidermis. - **Frequency:** Melanoma is less common than BCC and SCC, but it is the most aggressive and potentially deadly form of skin cancer. It accounts for a smaller percentage of skin cancer cases but is responsible for the majority of skin cancer-related deaths. - **Severity:** Melanoma has a high potential for metastasis if not detected and treated early. Early diagnosis is crucial, as it can spread to other organs. However, when detected in its early stages, melanoma is often curable through surgical removal. In summary, the three main forms of skin cancer are basal cell carcinoma (BCC), squamous cell carcinoma (SCC), and melanoma. They differ in appearance, cell origin, frequency of occurrence, and severity. BCC and SCC are more common, generally less aggressive, and have a lower risk of metastasis compared to melanoma, which is less common but more aggressive and potentially lethal if not treated promptly. Regular skin examinations and early detection are essential for effective treatment and improved outcomes for all types of skin cancer.