Keratoacanthoma: Why we treat it like squamous cell cancer.
Keratoacanthoma is a fairly common low-grade skin cancer that originates in the pilosebaceous glands. Pilosebaceous glands are the components of the deep layer of the skin (dermis) that hold the sweat glands, oil glands and hair follicles.
Keratoacanthoma tumors are characterized by rapid growth (up to 1-2 cm) over a few weeks to months (they can appear very abruptly). Commonly, they will then involute (spontaneously resolve) over the subsequent months to year. However, keratoacanthoma tumors can progress to squamous cell carcinoma and therefore need to be treated aggressively.
On gross examination, keratoacanthoma resembles squamous cell carcinoma (SCC). Further, on pathologic microscopic evaluation the two tumors look very similar. In fact, strong arguments support classifying keratoacanthoma as a variant of invasive SCC. In most pathology (biopsy) reports, dermatopathologists refer to the lesion as “squamous cell carcinoma, keratoacanthoma-type.” Since the two tumors are commonly indistinguishable from each other, keratoacanthoma is treated as if it were squamous cell carcinoma. This means that it need be excised (removed) with appropriate surgical margins. When treated appropriately, keratoacanthoma is believed to have a good prognosis.