Keratinizing squamous cell carcinoma is a distinct subtype of squamous cell carcinoma (SCC), which is one of the most common forms of skin cancer. The term “keratinizing” signifies that the cancer cells produce a notable amount of keratin, the same fibrous protein that constitutes hair and nails. This production of keratin often influences the physical appearance of the resulting lesion. This type of cancer originates in the squamous cells, which are flat cells found in the outer layer of the skin, known as the epidermis.
Causes and Associated Risk Factors
The development of keratinizing squamous cell carcinoma is most often linked to cumulative exposure to ultraviolet (UV) radiation from natural sunlight or artificial sources like tanning beds, which can cause damage to the DNA within skin cells. This damage disrupts the normal, orderly process of cell regeneration, leading to uncontrolled growth of abnormal squamous cells that can form a tumor. While UV light is the predominant cause, several other factors can increase an individual’s risk.
A compromised immune system, either from medical conditions like HIV/AIDS or from immunosuppressive drugs used after organ transplantation, elevates the risk of developing SCC. Certain infections, particularly with high-risk strains of the human papillomavirus (HPV), are also associated with an increased likelihood of SCC. Chronic inflammation resulting from long-term skin injuries, such as non-healing sores or burn scars, can also create an environment where this cancer may arise.
Personal and genetic factors are also important in determining risk. Individuals with fair skin, light-colored eyes, and blond or red hair are more susceptible to the damaging effects of UV radiation. A personal or family history of any skin cancer, including basal cell carcinoma or melanoma, predicts a higher risk of future skin cancers. Furthermore, the presence of precancerous lesions known as actinic keratoses indicates a higher risk for progression to invasive SCC.
Physical Signs and Body Locations
Keratinizing squamous cell carcinoma often appears as a persistent, non-healing lesion. A common sign is a firm, reddish nodule on the skin. Alternatively, it might manifest as a scaly or crusted patch that can be flat or slightly raised. Some lesions can take on the appearance of a wart or even form a “cutaneous horn,” a conical projection from the skin.
These growths can develop relatively quickly, sometimes over a period of weeks to months, and may become tender or painful to the touch. These lesions may bleed with minor trauma or to ulcerate, forming an open sore that resists healing. Any suspicious spot that fails to heal should be evaluated by a healthcare professional.
Common locations for these tumors include the face, particularly the lips and ears, as well as the neck, bald scalp, forearms, and the backs of the hands. It can arise on mucous membranes, such as inside the mouth, or in the genital region. In some cases, it can develop within existing scars or chronic ulcers.
The Diagnostic Process
Diagnosis begins with a thorough physical examination by a healthcare professional. During this exam, a doctor will inspect the skin for any suspicious growths, noting their size, shape, color, and texture. If a lesion raises concern for skin cancer, a skin biopsy is the definitive next step.
A biopsy is a procedure where a small sample of the suspicious tissue is removed for laboratory analysis. Several techniques may be used, such as a shave biopsy to sample the surface, a punch biopsy to take a deeper, circular sample, or an excisional biopsy to remove the entire lesion.
The removed tissue is then sent to a pathologist, a doctor who specializes in examining tissues to diagnose diseases. Under a microscope, the pathologist can confirm the presence of squamous cell carcinoma and identify it as the keratinizing subtype by observing the cancer cells producing keratin, sometimes forming structures called “keratin pearls”. The pathology report will also provide important details about the tumor’s characteristics, such as how deeply it has invaded the skin and whether it has involved nerves or blood vessels, which helps guide subsequent treatment decisions.
Medical Treatment Approaches
The primary goal of treatment for keratinizing squamous cell carcinoma is the complete removal of the tumor. For most cases, surgical excision is the standard approach. This procedure involves cutting out the cancerous lesion along with a surrounding margin of healthy skin to ensure all cancer cells are eliminated. The wound is then typically closed with stitches.
A specialized surgical technique called Mohs micrographic surgery has a high cure rate and is valuable for tumors in sensitive or important areas, like the face. In Mohs surgery, the surgeon removes the tumor layer by layer, examining each layer under a microscope until no cancer cells remain. This method maximizes the preservation of healthy tissue. For smaller, superficial tumors, a procedure known as curettage and electrodesiccation may be used, which involves scraping away the cancer and then using an electric needle to destroy any remaining cells.
Radiation therapy can be a primary treatment if a patient is not a suitable candidate for surgery or if the tumor is in a location that is difficult to operate on. It is also used as an adjuvant therapy after surgery if there is a high risk of the cancer returning, for instance, if the tumor was large or had aggressive features noted on the pathology report.
For advanced cases where the cancer has spread to lymph nodes or other parts of the body (metastasized), systemic therapies are necessary. Immunotherapy, which helps the body’s own immune system recognize and attack cancer cells, and chemotherapy are options.
Prognosis and Follow-Up Care
The prognosis for keratinizing squamous cell carcinoma is positive. When detected before it has grown deep into the skin or spread, the cure rates are high, often around 99 percent. The “keratinizing” nature of the tumor does not, by itself, indicate a worse outcome compared to non-keratinizing types. Factors that influence prognosis include the tumor’s size, its depth of invasion, its specific location on the body, and whether the patient has a weakened immune system.
Following successful treatment, lifelong follow-up care is necessary. Having one skin cancer increases the risk of developing another one in the future, so regular, full-body skin examinations by a dermatologist are necessary to detect any new or recurrent cancers.
Beyond medical check-ups, sun protection is a fundamental part of post-treatment care. This includes the consistent use of broad-spectrum sunscreen, wearing protective clothing such as hats and long sleeves, and avoiding peak sun exposure whenever possible.