A Clinical and Biological Review of Keratoacanthoma

A. Tisack; A. Fotouhi; C. Fidai; B.J. Friedman; D. Ozog; J. Veenstra


The British Journal of Dermatology. 2021;185(3):487-498. 

In This Article


Although the condition was initially described in 1888, the term 'keratoacanthoma' (KA) was coined in the 1940s to represent the marked acanthosis observed on histopathology.[1] However, 'keratocarcinoma' was also applied in the early literature to denote malignant potential, which stemmed from the many shared clinical and histological features with well-differentiated cutaneous squamous cell carcinoma (cSCC).[2] Thus, grouping KA with cSCC has been the standard for over a century. A marker to readily delineate them has yet to be identified, making definitive diagnosis and clinical management challenging given the disparate behaviour between the two lesions. Consensus between clinicians and pathologists on the diagnosis and treatment paradigm remains largely unresolved.[3]

Many strategies have been proposed to distinguish KA from cSCC, with limited success. A variety of histopathological criteria have been devised, but the abundance of similar morphological features has made differentiation on histopathological grounds alone dubious.[4] In an attempt to further dichotomize KA and cSCC, an array of immunohistochemical markers have been utilized, including cytokine signatures, cell adhesion markers, cell-surface receptors and regulators of the cell cycle and apoptosis.[5–14] Nevertheless, no strategy has reliably been able to predict biological behaviour.