Squamous cell carcinoma of the skin

Overview

Squamous cell carcinoma is a type of skin cancer that begins in squamous cells in the epidermis, the outer layer of the skin. It typically develops on parts of the skin that obtain the most sun exposure, such as the head, arms, and legs. It is the second most prevalent form of skin cancer. 

Squamous cells can be found throughout the body, and squamous cell carcinoma can develop anywhere with squamous cells. Cancer can also develop in areas of the body with mucous membranes, which are the inside linings of the organs and body cavities, such as the mouth, lungs, and anus.

There are two forms of squamous cell carcinoma depending on the location and the amount of cancer present in the body: 

• Cutaneous: A cancer that affects only the top layer of the skin (in situ) or cancer that has progressed beyond the top layer of the skin. 
• Metastatic: Cancer that has spread beyond the skin to other places of the body.

Squamous cell carcinoma of the skin is caused by a mutation to the p53 gene. The mutation happens due to extended exposure to ultraviolet (UV) radiation, which can come from sunshine or tanning beds or lamps. 

Squamous cell carcinoma of the skin is rarely fatal, but it can be aggressive. If left untreated, it can become large and spread to other parts of the body. Treatment options generally include surgery, special procedures, and medications. 

Symptoms

Skin changes can appear anywhere in the body even the insides of the mouth, bottoms of the feet, and on the genitals. Squamous cell carcinoma of the skin is most common on the scalp, backs of the hands, ears, or lips. These areas are at a high risk due to frequent exposure to the sun.

Squamous cell carcinoma symptoms include skin changes such as:

• A firm red nodule
• A rough–feeling lump or growth that may crust over like a scab and bleed
• A growth that is higher than the surrounding skin yet dips down at the center 
• A wound or sore that will not heal, or a sore that heals but returns
• A bigger region of flat, scaly, and red skin, about 1 inch 
• A rough and scaly patch on the lip that can progress to form an open sore.
• A patch that is red, sore, or rough inside the mouth.
• A patch that is raised and red or a sore resembling a wart on or inside the anus or on the genital area.

If you have a sore or scab that hasn’t healed for over two months, or a flat patch of scaly skin that persists, it is recommended to schedule an appointment with a doctor. Additionally, if you notice any new lump, mole, or changes to an existing mole or spot on your skin, it is important to seek medical attention.

Causes

Squamous cell cancer is caused by a p53 gene mutation. The most prevalent cause of p53 gene mutation is ultraviolet (UV) exposure from the sun or indoor tanning beds. The DNA of a cell includes the instructions that inform the cell what to do. The p53 gene instructs the cells to divide and reproduce to replace cells that have reached the end of their lifespan.

A p53 gene mutation means that the cells lack the instructions they require to function properly. As a result, the squamous cells divide and reproduce excessively frequently, resulting in the formation of tumors such as bumps, lumps, or lesions, in and on the body. Squamous cell carcinoma of the skin develops when the DNA of the flat, thin squamous cells in the middle and outer layers of the skin changes or mutates.

However, sun exposure does not explain skin cancers that originate on skin that is not normally exposed to sunlight. This suggests that other variables may increase the likelihood of skin cancer. 

Risk factors

Several factors can contribute to one’s risk of developing squamous cell carcinoma of the skin, such as:

• Fair skin: Squamous cell carcinoma of the skin can occur in people of any skin color. Nevertheless, individuals with less melanin in their skin are at a higher risk because they have less natural protection against harmful UV radiation. 

People with blond or red hair, light–colored eyes, and freckles are more susceptible to squamous cell carcinoma compared to people with darker complexion.

• Prolonged sun exposure: Having long–term sun exposure or solar damage or UV light at an early age can raise the risk of squamous cell carcinoma. 
• Use of tanning beds: Squamous cell carcinoma is more likely to develop in people who use indoor tanning beds. 
• History of sunburns: People who sunburn easily are more likely to develop squamous cell carcinoma, especially when one has suffered sunburn as a child or adolescent. 
• History with precancerous skin lesions: The chance of developing squamous cell carcinoma of the skin is greater in people with a precancerous skin lesion, such as actinic keratosis or Bowen’s disease. 
• History of skin cancer: Recurrence of squamous cell carcinoma of the skin is possible to those who had it before. 
• Weakened immune system: Immunocompromised people such those who had organ transplants, leukemia, or lymphoma are at a higher risk of developing skin cancer.
• Rare genetic disorder: A condition that causes extraordinary sensitivity to sunlight known as xeroderma pigmentosum, can potentially result in acquiring skin cancer.