A keratoma is a common, localized skin growth composed of keratin, the tough, fibrous protein that makes up the outer layer of skin. These growths are generally benign, but the term encompasses a spectrum of lesions, some of which are precancerous. A keratoma forms when keratinocytes (skin cells) reproduce excessively, leading to a buildup of keratin on the skin’s surface. Proper identification of these lesions is important for guiding necessary management.
Defining Keratomas and Their Appearance
Keratomas manifest in varied ways, with the two most frequently encountered types being Seborrheic Keratoses (SK) and Actinic Keratoses (AK). Seborrheic keratoses are non-cancerous lesions that often develop after middle age, appearing on the back, chest, face, or neck. These growths have a characteristic “stuck-on” or waxy appearance, as if they could be easily scraped off. SKs can range in color from light tan to dark brown or black, and their texture may be smooth, warty, or scaly.
Actinic keratoses (AKs) are considered precancerous and are directly related to sun damage. They typically present as dry, rough, or scaly patches that may be felt more easily than they are seen. AKs are often smaller than an inch and can be skin-colored, pink, red, or brown. They are commonly found on areas of chronic sun exposure, such as the face, ears, lips, scalp, forearms, and hands. A small percentage of untreated AKs can progress into squamous cell carcinoma.
Underlying Causes and Risk Factors
Keratoma formation stems from a disruption in the normal life cycle of keratinocytes, the cells that produce keratin. The primary cause for Actinic Keratoses is chronic, cumulative exposure to ultraviolet (UV) radiation from the sun or tanning beds. This UV damage causes mutations in the skin cells, leading to abnormal growth patterns. Risk factors for developing AKs include being over 40 years old, having light skin and eyes, and a history of frequent, intense sun exposure.
Seborrheic keratoses are strongly linked to aging, which is why they are sometimes called “senile warts.” Genetic predisposition plays a large role in SK development, with many individuals reporting a family history of the growths. They tend to increase in number and size as a person gets older, appearing most commonly in areas covered by clothing.
Diagnostic Procedures and Evaluation
A dermatologist can often identify a keratoma through a simple visual examination. To enhance this assessment, a handheld dermatoscope is frequently used, which provides magnification and polarized light to visualize structures beneath the skin. Dermatoscopy is effective for distinguishing between benign growths, like seborrheic keratoses, and more serious lesions, such as melanoma. This non-invasive tool helps the physician look for specific patterns indicative of keratin overgrowth or malignancy.
If the diagnosis remains uncertain, especially if the lesion suggests skin cancer, a skin biopsy is performed. A shave biopsy is often used for raised lesions, where a thin layer is shaved off and sent to a pathology lab for microscopic evaluation. This procedure, performed under local anesthesia, confirms the diagnosis and rules out squamous cell carcinoma or other malignancies.
Management and Removal Options
Intervention for keratomas is generally chosen based on whether the lesion is precancerous, causes symptoms like itching or irritation, or if the patient desires cosmetic removal. Actinic keratoses are typically treated because of their potential to develop into skin cancer. One common method is cryotherapy, which involves applying liquid nitrogen to freeze and destroy the abnormal cells. This causes the lesion to blister and eventually fall off.
For widespread or multiple Actinic Keratoses, topical treatments are used to treat an entire area of sun-damaged skin, known as field therapy. Creams containing 5-fluorouracil (5-FU) inhibit DNA synthesis in rapidly dividing cells. Imiquimod stimulates the immune system to target the abnormal cells. These topical regimens can last several weeks and often cause temporary inflammation and redness.
Seborrheic keratoses are often removed using curettage and electrodessication. Curettage involves scraping the lesion off the skin surface with a specialized loop-shaped instrument. Electrodessication uses an electric current to cauterize the base and stop bleeding. Larger or unusually shaped keratomas may require surgical excision, where the lesion is completely cut out and the wound is closed with stitches.