Which of the following skin conditions is considered benign and has the lowest risk of malignancy?

Keratoacanthoma is a skin condition that is often considered benign and typically has a lower risk of malignancy compared to the other options presented. Although keratoacanthomas can resemble squamous cell carcinoma both histologically and clinically, they are generally self-limiting and tend to regress without treatment. The growth pattern is characterized by a rapid increase in size, followed by a period of involution.

In contrast, squamous cell carcinoma and basal cell carcinoma are both types of skin cancers, with the former presenting a higher risk for metastasis and the latter being the most common skin cancer but generally localized and rarely metastasizing. Actinic keratosis, while not inherently malignant, is considered a precancerous condition as it can progress to squamous cell carcinoma if left untreated. Hence, keratoacanthoma stands out as the benign condition among these options, demonstrating the lowest risk of progression to malignancy.