A keratoacanthoma is a rapidly growing, well-differentiated neoplasm of squamous epithelium. It assumes a distinct crater-shaped appearance and usually occurs as a solitary lesion on sun-exposed skin. Men are more commonly affected than women, individuals with lighter skin phototypes are at greater risk than those with darker skin phototypes, and peak incidence is between 65 and 71 years of age.

A periocular keratoacanthoma appears and grows rapidly over the course of a few weeks to months. Lesions involving the eye may produce mechanical abnormalities, such as ectropion or ptosis, and, occasionally, may cause destructive changes. If left untreated, some keratoacanthomas spontaneously involute within 6 months, but they may resolve with scarring and destruction of ocular adnexa.

Risk factors include ultraviolet (UV) light exposure and immunosuppression. Skin injury may also be a predisposing factor, as there are many reports of keratoacanthomas developing in sites of previous trauma, in surgical scars, after laser resurfacing, and following radiation therapy. Foreign bodies, such as tattoo ink, have also been identified as risk factors for keratoacanthomas.

Many consider keratoacanthomas to be a low-grade variant of squamous cell carcinoma. Most will cause only local destruction. Due to the very thin skin of the eyelid, these lesions are particularly susceptible to extension into underlying stroma and even orbicularis oculi muscle. More invasive variants, with metastasis to draining lymph nodes or the cavernous sinus, have been reported.