Keratoacanthomas are relatively common skin tumors, especially among older individuals. The majority of patients are over 60 years old. They occur approximately twice as often in men as in women.
Keratoacanthomas appear as noticeable skin tumors with a central "crater". The crater is filled with keratinized material (keratin and dead cells), alternatively with ulceration and/or crust formation. Often, there is some redness at the edge of the tumor, which indicates an inflammatory reaction.
Typical locations for keratoacanthomas are the face, ears, and arms (particularly the back of the hands). A keratoacanthoma grows rapidly within 1-3 months and reaches a size of approximately 1-2 cm. With the correct diagnosis, most keratoacanthomas will spontaneously regress within six months. They often leave a scar. Distinguishing a benign keratoacanthoma from various forms of skin cancer, especially squamous cell carcinoma, can be challenging. In most cases, tissue samples are necessary, preferably by surgically removing the entire tumor for further examination.
Keratoacanthomas arise from cells related to the hair follicles and are commonly seen in areas exposed to a lot of sunlight. The exact reasons for the development of these skin tumors are not fully understood, but sun damage is likely a significant factor. Individuals with weakened immune systems or those being treated with immunosuppressive medications (such as organ transplant recipients) have an increased risk of developing keratoacanthomas. The role of smoking, chemical exposure, and human papillomavirus (HPV) in this condition is still under discussion.
Keratoacanthomas are surgically removed under local anesthesia. Ideally, the entire tumor is excised and sent for microscopic examination. There are other treatment options, but these are reserved for a select group of patients.
The major challenge with keratoacanthomas is differentiating them from malignant skin tumors, including squamous cell carcinoma. Therefore, the pathologist's histopathological examination and assessment are crucial. The diagnosis is based on several factors, including development (rapid growth, spontaneous regression), appearance, and microscopic examination.
